bluuebunny/crossref_metadata_2025_split huggingface dataset:
The burrowing process of Dentalium (Scaphopoda)
Authors: Trueman E. R. 
Published: August 2009

Investigations of the burrowing activity of Dentalium, using cine film and electronic recording techniques, have shown it to penetrate the sand in a series of steps, each termed a “digging cycle”. Cycles involve first, pedal dilation, second, retraction followed by extension and probing of the foot. The epipodial lobes are elevated during pedal dilation and form a secure pedal anchor so that at retraction the shell is drawn down over the foot.A comparison of the burrowing process in the Scaphopoda with that of the Bivalvia indicates that essentially the same mechanisms and sequence of activities are involved, for in both digging consists of the integration of pedal protraction and retraction with the application of shell and pedal anchors. The principal differences, such as the absence in Dentalium of water jets to loosen the sand and high pressures in the pedal haemocoele, are related to the form of their shell. The strength of the pedal anchor was determined and, relative to the weight of Dentalium, is comparable to that of bivalves. In contrast the probing force was relatively weak since the shell anchor of Dentalium, which holds the shell still during probing, is largely limited to its own weight, whereas that attained by the Bivalvia is principally due to the valves being pressed against the substrate by the opening moment of the ligament.
The effect of temperature on the life cycle, growth and fecundity of Branchiura sowerbyi (Oligochaeta: Tubificidae)
Authors: Aston R. J. 
Published: August 2009

Branchiura sowerbyi Beddard was probably introduced to Britain with exotic plants consigned to botanic gardens. The British populations occur mainly in artificially warmed habitats such as lily ponds in botanic gardens and power station effluents but a few are found at natural temperatures. Branchiura completed its life cycle in about a year both in the river Avon, Wiltshire, at natural temperatures and in the warm effluent from a power station discharging into the river Thames. In a worm culture maintained at natural temperatures the rate of cocoon production reached a peak in summer and was closely related to temperature.In the laboratory it was found that the optimum temperature for cocoon laying in mature worms, also growth in sexually immature worms, was near 25°C. The optimum temperature for growth in sexually mature worms, however, was lower (10°C in the Avon population and 15°C in the Thames population). It followed that at 20°–25°C the growth of sexually mature worms was probably depressed by the high rate of cocoon production.
The effect of gluteal muscle ablation on the pelvis of the laboratory rat (Rattus norvegicus)
Authors: Ashton E. H. , Moore W. J. 
Published: August 2009

Ablation of the gluteal muscles in rats, three weeks old, has been shown to result in an average diminution of 7 % in the other blocks of hip muscles. Concurrently, the weight of the innominate bone is reduced by 7 % and its dimensions by an amount varying between 1 % and 8 % and averaging about 3 %. This reduction in size and weight is comparable with that obtaining in the rat skull following bilateral masseterectomy.The dimensions of the innominate bone most affected by the reduction in muscular pull are those of the iliac blade, whose proportions, however, remain unaltered–a finding indicative of an appreciable measure of genetic control of this feature.
Notes on the life‐history and ecology of Tachypodoiulus niger (Diplopoda, Iulidae) in Britain
Authors: Blower J. Gordon , Fairhurst Colin P. 
Published: August 2009

In some iulids females can moult several times after first attaining maturity but males cannot. Males of Tachypodoiulus niger (Leach) are exceptional in that they can moult, but they lose their functional intromittent organs in the process, regaining them after a second moult. The process can be repeated, a series of functional males alternating with nonfunctional males. This extension of the life and the consequent increase in number of segments led Verhoeff (1928) to postulate that the ancestral millipede was short‐bodied and that many‐segmented forms were derived from it. We think that this extension of life is of ecological rather than phylogenetic significance–adapting the species to disperse widely to scattered habitats. In particular, the extension of life of males as well as of females may ensure a reasonable sex ratio in those areas where the species is least dense.In Britain, Tachypodoiulus niger lays eggs in spring which reach the fourth and fifth stadia by their first winter and the seventh, eighth and ninth stadia by their second winter. Maturity is usually attained by males in the eighth stadium but occasional specimens mature at stadium seven and others defer maturity until the ninth. Both sexes can proceed to the fourteenth stadium but adults in Britain usually belong to two generations of two and three years old, divided mainly between the eighth, ninth and tenth stadia. Details are given of a large collection made by the late Dr Scott of animals taking refuge in his house at Henley‐on‐Thames. Animals in Britain appear to have a similar life history to those in Germany as described by Verhoeff, but effective comparison has depended on correcting and re‐interpreting some of Verhoeff's data.
A comparison of the locomotion of two desert‐living Australian mammals, Antechinomys spenceri (Marsupialia: Dasyuridae) and Notomys cervinus (Rodentia: Muridae)
Authors: Marlow B. J. 
Published: August 2009

The locomotion of the marsupial, Antechinomys spenceri and the rodent, Notomys cervinus was studied by recording their tracks on long strips of smoked kymograph paper and by means of slow‐motion cinematography. Although both animals occupy the same habitat and are similar in their general appearance, their methods of locomotion differ greatly, since Antechinomys leaps quadrupedally, while Notomys leaps bipedally at fast speeds and runs quadrupedally at slower speeds. The mean speed of both genera was 2.7 m/sec but the mean length of stride of Notomys was 51.2 cm compared with 44.3 cm in Antechinomys. The locomotion of the two Australian genera is compared with that of the North American rodents, Dipodomys and Microdipodops.The significance of the different types of locomotion is discussed.
Breeding seasons of sea‐birds in the Galapagos Islands
Authors: Harris M. P. 
Published: August 2009

The sea‐birds breeding in the Galapagos Islands show a diversity of breeding cycles. Some species have rigidly fixed annual breeding while others breed throughout the year but have peaks of breeding at less than annual intervals. The eight species which have non‐annual breeding are probably breeding as often as possible with the interval between the end of a breeding attempt and the start of the next being the time needed to moult the wing and tail feathers. Only one species is definitely known to breed and moult at the same time.Although there are well marked seasonal fluctuations in the sea temperature, regular sampling failed to demonstrate any regular fluctuations in the surface plankton. The available evidence suggests that food for some sea‐birds is erratic and unpredictable. Some non‐annual breeding species have their breeding synchronized by severe food shortages which delay breeding, presumably because females cannot find enough food to form eggs, until conditions improve.Timing of the breeding season in annual breeders is less easily explained but some species may be feeding well away from the islands in areas where there is a regular fluctuation in the food supply. Most of the annual breeders have prolonged breeding seasons and in two species breeding is out of phase on different islands. Perhaps species are influenced by some weak annual variation in food supply which makes it disadvantageous to breed in a few months of the year.
The atlas‐axis complex of the mammal‐like reptiles
Authors: Kemp T. S. 
Published: August 2009

The atlas‐axis complexes of four of the major groups of the mammal‐like reptiles are discussed. These represent the four principal types of occipital condyle found in the Synapsida: hemispherical in the pelycosaurs, kidney‐shaped in the gorgonopsids, trefoil‐shaped in the dicynodonts and double in the cynodonts. In each case the possible movements of the skull are analysed in detail. It is shown that the central theme of the wide variation of this structure found within the synapsid reptiles is the manner in which the problem of achieving rotation of the head about a longitudinal axis was solved.An attempt is made to elucidate the functional evolution of the atlas‐axis complex within these reptiles and the significance of the differences between the reptilian and the mammalian complexes is noted.
Comparative aspects of the fine structure of the eyes of Phalangida (Arachnida) and certain correlations with habitat*
Authors: Curtis D. J. 
Published: August 2009

The eyes of seven species of Phalangida (Arachnida) were studied using electron microscope techniques. A fairly typical uni‐lenticular ocellus, the phalangid eye has beneath the lens a glassy body of lentigen cells, which are separated from the retina by a pre‐retinal membrane. The retina consists of hexagonally packed cylindrical retinulae, directed towards the dioptric apparatus. Each retinula comprises four cells, each of which contributes to the central cylindrical rhabdom by means of microvillar foldings of their plasma membranes. The only other cells in the retina constitute the glial system, with their somas situated proximally and with long cylindrical processes, each characterized by a central microtubule, passing distally in the interstices between the retinulae. Although there are none in the retina, laterally sited pigment cells prevent stray light entry, aided by cuticular pigmentation and hypodermal cell inclusions.The eyes of the various species show similarities correlated with their common function: sublenticular membrane modifications, many pigment granules separating the rhabdoms, many well‐developed mitochondria in the photoreceptor cells and many rhabdomal microvilli providing a large membrane surface area for photoreception. Distal rhabdom fusion could possibly serve either to transmit excitation between rhabdoms (providing increase in sensitivity) or, less likely, inhibition (providing increase in acuity). Peri‐rhabdomeric vesicles in all the species are functionally significant.Some interspecific differences may be considered to have a purely physiological basis, such as the relative abundance of rough endoplasmic reticulum in the lentigen cells, the condition of the pre‐retinal membrane, variations in microvillar diameters etc. Other differences, such as the relative height of the lentigen cells, may be correlated with ecological factors. The extreme differences in the eyes of Nemastoma lugubre (very short lentigen cells, disorganized rhabdoms, cellular sheath behind eye) possibly indicated some degree of regression, correlated with the animal's environment.
A comparative study of the integument of the camel, Dorcas gazelle and jerboa in relation to desert life
Authors: Ghobrial Laurice I. 
Published: August 2009

Comparative histological studies of the integuments of the Dorcas gazelle, jerboa and camel have revealed the presence of tubular sweat glands in the skin of the Dorcas gazelle and the camel but not in the jerboa.Hairs occur in groups in the skin of jerboa and camel but occur singly in the Dorcas gazelle where they are of two types; short under hairs and long covering hairs. Each hair follicle is associated with a sebaceous gland. Both the unkeratinized epidermis and its horny layer are comparatively thin in the jerboa and gazelle, and in dry air this may permit greater loss of water by transpiration than in the camel which has a comparatively thick epidermis.
The life cycle of Thomisus onustus (Thomisidae: Araneae) and outlines for the classification of the life histories of spiders
Authors: Levy Gershom 
Published: August 2009

The life cycle of the spider Thomisus onustus, with its two adult phases annually, is elucidated. Differences between males and females, in the length of the developmental period up to maturity, excluded the possibility that siblings could mate in nature. Females maintain a stable cycle of one year, whereas the males show a change in the length of their developmental cycle, according to the phase from which they originate. The variance which occurs among spiderlings, in regard to the number of moults and the length of the different instars is discussed.Outlines for a general classification of the life histories of spiders is being suggested.
New species and a new subgenus of Spirorbinae (Serpulidae: Polychaeta) from Kenya
Authors: Knight‐Jones Phyllis 
Published: August 2009

Four species were collected, all attached to marine angiosperms, Pileolaria daijonesi sp.n. being the most abundant. The other three have the collar folds fused dorsally, as is characteristic of Dexiospira (=Neodexiospira Pillai), which is here regarded as a subgenus of Janua. Janua (Dexiospira) formosa (Bush) and Janua (Dexiospira) steueri Sterzinger are distinguished clearly from one another for the first time and shown to be widely distributed in warm seas. Janua (Fauveldora) kayisubgen. et sp. n. is a very closely related sinistral form, which extends to the Persian Gulf and Ceylon.Reviewing serpulids, it seems that the primitive position of the operculum in Serpulinae and Spirorbinae was sinistral. The most recent changes involving this character, however, have been situs inversus back‐mutations, from stocks which are dextral and presumably more labile.Summary:Four species from Kenya were all opercular incubators and attached to marine angiosperms, Pileolaria daijonesisp.n. being much the most numerous. The other three all have the collar folds fused dorsally, but should be placed in the redefined genus Janua, two falling indisputably into the redefined subgenus Dexiospira (=Neodexiospira Pillai). These two, J. (D.) formosa Bush and J. (D.) steueri Sterzinger, are redescribed and distinguished clearly from one another for the first time, the easiest distinction being that the blades of the abdominal setae are broad in the former and narrow in the latter. Both are shown to be widely distributed in warm seas. The remaining species, Janua (Fauveldora) kayisubgen. et sp.n., which extends to the Persian Gulf and Ceylon, is closely related to Dexiospira, but its operculum and related coiling are sinistral. Reviewing these characters in serpulids generally, it seems clear that the primitive position of the operculum in Serpulinae and Spirorbinae was sinistral, that many Spirorbinae have become dextral and that the most recent evolutionary changes, involving this character, have been back‐mutations from such dextral stocks.
Some aspects of the functional morphology and biology of Pseudopythina subsinuata (Bivalvia: Leptonacea) commensal on stomatopod crustaceans
Authors: Morton Brian 
Published: August 2009

Pseudopythina subsinuata (Lischke) has been found in Hong Kong waters to be commensally associated with the following stomatopod crustaceans: Oratosquilla perpensa (Kemp), Oratosquilla interrupta (Kemp), Oratosquilla oratorio (De Haan), Harpiosquilla japonica Manning. The location on the host is highly specific.Studies on the functional morphology and biology of this bivalve have shown that it is relatively unspecialized except with regard to its sexual cycle. It has been shown to be a protandric hermaphrodite in which a smaller male normally occurs in close association with a larger female. Fertilization occurs in the supra‐branchial chamber of the female and the young are subsequently incubated in the same position. Solitary females also occur.It is suggested that a complex sexual cycle was a prerequisite for the successful exploitation of the commensal mode of life by the Leptonacea in general and that subsequent morphological specializations have occurred in only some.Summary: Pseudopythina subsinuata has been found in Hong Kong waters living commensally on the following species of stomatopod crustaceans: Oratosquilla perpensa (Kemp), Oratosquilla interrupta (Kemp), Oratosquilla oratorio(DeHaan), HarpiosquiliajaponicaManning. [ts location on the host is extremely specific and is occasioned by the requirements of the commensal and the limitations imposed by the behaviour of the host. Pseudopythina subsinuata possesses many characters which suggest that it has only comparatively recently adopted a commensal mode of life:(1) It is not host specific.(2) It possesses a large shell with distinct hinge teeth.(3) The mantle edges are not reflected over the shell, and there is no inhalant siphon.(4) There is a well developed byssal apparatus.(5) The stomach is large, not reduced and non‐specialized.(6) The style sac still retains a connection with the mid‐gut along half its length.Some of these primitive characters, e.g. the large byssus, have been retained because they possess an obvious survival value. Other characters, e.g. the large labial palps, and the absence of interlamellar junctions in the ctenidia are probably specializations.The sexual cycle of Pseudopythina subsinuata is complex, the animal being a protandrous consecutive hermaphrodite. Solitary females also occur in the population. Fertilization occurs in the supra‐branchial chamber and the young are incubated there at least until the late veliger stage.It is suggested that a highly specialized sexual cycle was developed early in the evolution of the Leptonacea and was a prerequisite for the successful adoption of a commensal mode of life. Anatomical specializations evolved later, and to different degrees in different phylogenies.
The effect of wind on shore gastropods
Authors: Courtney W. A. M. 
Published: August 2009

A preliminary investigation into the effect of wind on shore gastropods has been undertaken. Moderate winds displace some Monodonta lineata (da Costa) from boulders on the shore and some individuals detach within six hours in weaker winds in the laboratory (5–10 km/h, 10°C, 94% humidity). Sheltered aspects of the rock are used to minimize the effects of the wind on shores, and maintenance movements on the shore are extensive.Summary:In calm conditions and in light winds Monodonta lineata is more widely dispersed about the rocks than in moderate winds when the animals are either sheltering in cracks or displaced.Providing the rock surface is damp then animals continue to move about during emersion in light winds. On a small boulder beach animals moved as much as 4 m upshore during one tidal cycle. Only slight reorientation movements were recorded during moderate winds.Animals withstand a windspeed of 4 km/h for six hours in a wind tunnel in a humidity of 94% at 10°C, but are displaced within an hour by 10 km/h winds in similar conditions.
The setae of Eurydice pulchra (Crustacea: Isopoda)
Authors: Fish Susan 
Published: August 2009

The setal armature of Eurydice pulchra Leach is described using an ordinary optical microscope. On the basis of size, setae are divided into macrotrichs and microtrichs. Macrotrichs are further classified according to structural similarities into four groups. Only two types of microtrichs have been recognized. The distribution of the different setae on both adults and juveniles is described and where possible an attempt is made to relate morphology and distribution to function.Summary:The setal armature of E. pulchra has been divided into macrotrichs, varying in length from 0·025 to 0·4 mm, and microtrichs varying in length from 2 to 10 μm. The macrotrichs have been classified into groups based on structural similarities and 17 distinct types have been recognized. Each differ in length, degree of chitinization and modification of the shaft wall. The distribution of the macrotrichs has been described and particular types have been shown to occur in distinct positions on the body. Many of the macrotrichs are peculiar to one position on the body.Two types of microtrichs have been described, a single type approximately 10 μm in length and a smaller type 2 μm in length. The latter occurs in short crescentic rows principally on the pleopods and oostegites. All setal types occurring in the adult have been shown to be present in the newly emerged juvenile although the number developed is very much less. Similar setal types are present in males and females. An attempt has been made to relate the morphology and distribution of both macrotrichs and microtrichs to possible functions.
Surplus killing by carnivores
Authors: Kruuk Hans 
Published: August 2009

In several field observations, foxes, Spotted hyaenas and other carnivores killed many more prey individuals than they could eat. Functional and causal aspects of this phenomenon are discussed and the conclusion is reached that these surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmental requirements.Summary:(1) Observations are reported in which carnivores killed considerably more prey animals than they could possibly eat, and causal and functional aspects of this behaviour are discussed. The species concerned were especially foxes and Spotted hyaenas, and references are quoted about surplus killing by other Canidae, Felidae and Ursidae.(2) It is argued that satiation in carnivores does not inhibit further catching and killing, but it probably does inhibit searching and hunting. Thus carnivores are able to procure an “easy prey” but normally satiation limits numbers killed.(3) Many, if not all, carnivores possess behaviour patterns which allow utilization of a kill at a later time, or allow other members of the same social unit or offspring to use the food.(4) Several prey species showed a lack of anti‐predator reaction under particular climatological circumstances; it is argued that this lack of response usually has survival value. Sometimes anti‐predator behaviour is accidentally made ineffective.(5) Surplus kills are made possible by (2) and (4) above, and only very rare circumstances give a predator access to so many prey that (3) is ineffective. It is suggested that surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmental requirements.
Nature of the air‐breathing organs of the Indian fishes Channa, Amphipnous, Clarias and Saccobranchus as shown by electron microscopy
Authors: Hughes G. M. , Munshi J. S. Datta 
Published: August 2009

The structure of the air‐breathing organs of the Indian fishes Channa punctatus, Channa Striatus, Amphipnous cuchia, Clarias batrachus and Saccobranchus fossilis has been investigated using electron microscopy. In all species the barrier separating the air from the blood consists of three main layers (epithelium, basal lamina and endothelium). The total thickness ranging from 0.78 μm in C. punctatus 1.6 μm in S. fossilis.In Clarias and Saccobranchus the presence of pillar cells characteristic of gill secondary lamellae confirms evidence for the origin of these organs by modification of a typical gill structure.In Amphipnous and two species of Channa, however, the evidence suggests that the accessory organs represent modified gills. The presence of valve‐like structures between the afferent and efferent blood spaces of the vascular papillae gave the appearance of pillar cells under the light microscope.The structure of these organs is correlated with physiological studies on the degree of their importance in the life of the animal and the degree of gill development
The structure of encysted sperm of some British Pseudoscorpiones (Arachnida)
Authors: Legg Gerald 
Published: August 2009

The sperm of pseudoscorpions consists of a coiled head (nuclear material), axial filament and an “annular” mitochondrion, all enclosed within a cyst.Variations occur in the gross morphology of different pseudoscorpion sperm. These variations are discussed in terms of possible morphological relationships.