MYRIAPODA,

A wingless tribe of insects, formerly so called, of which centipedes (the genus Scolopendra of Linnaeus) form the most characteristic example, are now regarded as a separate class of the articulated tribes, in conformity with the views of Dr Leach and other writers who have studied their structure and economy. Under this title, therefore, as formerly intimated,^[1. See the article Entomology of this work, vol. ix. p. 59, foot note. ] we shall present the reader with a brief notice of the principal genera, of which the prevailing forms have been already exhibited (in connection with our representations of insects) on Plate CCXXXIX. of this work. We owe the establishment of the class to Dr Leach,^[2. Linn. Trans. xi. 376. ] Μ. Lamarck having viewed the Myriapoda as arachnides,^[3. ’ Animaux sam Vertèbres, v. 24. ] while Μ. Latreille, except in a single work,^[4. Familles du liègne Animal, p. 322. ] regarded them as true insects. As such they were likewise included by Linnaeus, and the older systematic writers, in the order Aptera.

The Myriapoda are distinguished from true insects by their greater amount of feet (twenty-four and upwards), by the want of any precise or appreciable division into thorax and abdomen, and by the numerous segments into which their bodies are divided. Each segment, with the exception of the first, is furnished with a pair of legs, terminated for the most part by a single hook. The stigmata, or openings for respiration, are placed on each alternate segment, a circumstance which has induced some observers to regard the latter as only semi-segments, in as far as in true insects each ring has its pair of stigmata. But we see no necessity for the establishment of any strict analogy of form between the subjects of two distinct classes of articulated beings; and indeed, if we do so in regard to the character in question, we produce a greater discordance by the necessity, in that case, of assigning to each so-called (double) segment, a couple of pair of legs. The mandibles are bi-articulate, and are followed by a piece in the form of a labium, quadriful, with articulated divisions resembling little feet, and corresponding in position to the languette of the Crustacea. Then succeed two pair of small feet, of which the second, sometimes hook-shaped, seem to replace the four maxillae of the last-named order, or the two maxillae and the lower lip of insects. They may be regarded as maxillary feet. The antennae are two in number. Their form cannot be easily generalised, because, although they may often be, as Latreille says, “courtes, un peu plus grosses vers le bout, ou presque filiformes yet in some (genus Scutigera) they are very long, and become much more slender towards the extremity. The number of the articulations also varies greatly. The organs of vision are usually formed by a union of smooth or simple eyes; but in some these parts are analogous to the compound eyes of insects, the facettes, however, being proportionally larger, rounder, and more distinct. All Myriapodes are apterous.

The subjects of our present notice differ likewise from insects in this remarkable peculiarity, that the number of their segments, and consequently of the stigmata and legs, increases with the size of the individual. It would even appear, from the observations of Savi the younger,^[5. » Memorie Scientijiche, Pisa, 1828. ] that the genus lulus is born without feet; from which it has been observed, that those Myriapodes are subject, at some early period of their lives, to a regular metamorphosis. Degeer had long before observed, that the number of their parts increased with the general growth of the body.

The organs of respiration consist of two principal tracheae extending parallel along the body, and receiving air from the lateral spiracles.

Myriapodes are generally supposed to be longer lived, and of more continuous growth, than insects; and, according to Savi the younger, two years elapse (at least in the genus lulus) before the development of the generative system; but it must be borne in mind, that many insects exist for a length of time in the larva state (to which the early condition of the Myriapodes so closely corresponds), and are thus of equal longevity with the many-footed subjects of our present inquiry. The Myriapodes in general shun the light. They conceal themselves under stones, beneath the bark of trees, among old timber, and in various other localities. Some inhabit fruits, and others are destructive to culinary vegetables. Many are carnivorous, seizing upon animal substances, both dead and living, with their curved jaws. They are said to infuse a poisonous juice into their wounded victims.

In our subdivision of the class, as in the preceding generalities, we shall follow the system of Latreille, by whom the Myriapodes are partitioned into two primary groups, which differ from each other both in habits and structure.

Order L—CHILOGNATHA.

This primary group corresponds to the genus lulus of Linnaeus. The body is for the most part cylindrical, and of a crustaceous consistence. The antennae are composed of seven joints, of nearly equal size. The mandibles are thick, without palpi, distinctly divided into two portions by a median articulation, and with teeth implanted in a concavity of their upper extremity. Beneath is a kind of labium or lower lip, divided at its exterior surface, by [7:15:653] notches and longitudinal sections, into four principal areas, tuberculated on the upper margin, and of which the two intermediate are short and narrow, and placed at the upper extremity of another area, which serves them as a common base. The feet are very short, and always terminate in a single hook; four anterior feet placed immediately beneath the labium, resemble the others in form, but are more approximate at their base, with the radical joint proportionally longer. Most of the other legs are attached by double pairs to a single segment of the body. The male organs are placed beneath the seventh pair of legs, those of the female behind the second pair. The stigmata, as usually described, are very small, and placed on alternate segments outside the origin of the legs.

The Myriapodes of this division are slow of movement, and advance, as it were, by a gliding motion. They assume in defence a round or spiral form. The first segment of the body, in some the second, is larger than the others, and presents the form of a corselet or buckler. The double pairs of legs do not occur until we reach the fourth, fifth, or sixth pair; the first three or four pair being free from their origin, or adhering to their respective segments only by a median or sternal line. The*two or three terminal segments of the body are usually without feet. On each side of the body there is a series of pores, formerly regarded as stigmata, but which, according to Μ. Savi, merely emit an acid liquor of a disagreeable odour, and probably intended as a means of defence; the true stigmata, or respiratory openings, as described by the Italian naturalist, being placed on the sternal piece of each segment, and communicating internally with a double series of pneumatic pouches, disposed en chapelet along the body, and giving out tracheal branches, which ramify over the other organs. These pouches or vesicular tracheae, according to Μ. Straus, are not connected with each other, as among ordinary insects, by a principal trachea.

The form of the newly-hatched bodies of the lulidae, as observed by Μ. Savi in the vicinity of Pisa, was somewhat kidney-shaped, quite plain, and without appendages. After the lapse of eighteen days they underwent their first moult, and only then assumed the form of the adults; but they were still composed of only twenty-two segments, and the total number of their legs amounted to twenty-six pair. These observations are in some measure inconsistent with the assertion of Degeer, who in the young state of these creatures counted only three pair of legs and eight segments: but is it certain, asks Μ. Latreille, that the moult described by Μ. Savi was actually the first; or ought we not rather to presume that they do not pass suddenly from an apodal state to the possession of twenty-six pair of legs; in other words, that they are subject to certain intermediate changes, which may have escaped the observance of Μ. Savi?^[6. Règne Animal, iv. 332. ] After the second moult, however, the last-named naturalist informs us, the genus lulus exhibits thirty-six pair of legs, and after the third, forty-three, and the body then consists of thirty segments. In the adult state the number is considerably increased. Two years afterwards another moult takes place, and it is only then that the generative system is developed. From the period of birth, which takes place in March, the renewals of the skin were observed by Μ. Savi to take place almost monthly till November, and the exuviae were seen to contain even the membrane which lines the interior of the alimentary canal and tracheae. The organs of the mouth were the only parts not there observed by Μ. Savi.^[7. See Osserυazione per servire alla storia di una specie di Iulus communissima, reprinted in Memorie Scientifiche, Pisa, 1828. ]

The food of these Myriapodes consists both of animal and vegetable substances, generally dead and decomposed. They deposit a great number of eggs. The generic groups are as follows. We shall enter into few details, as we have illustrated so many of the prevailing forms by means of accurate figures.

Genus Glomeris, Lat. Body convex above, concave below, with a range of small scales along the lower sides. It is composed of twelve segments, exclusive of the head. The male has thirty-two legs, the female thirty-four.

The species are not numerous. Although G. ovatus inhabits the sea, the greater proportion arc terrestrial, occurring under stones, particularly in mountainous countries. G. marginata (Plate CCXXXIX. fig. 1) is common in most European countries.

Genus Iulus, Lat. Body cylindrical and extended, without any projecting crests or cutting margins.

The larger species are terrestrial, and live in woods; the smaller attack fruits, roots, and various kitchen produce, to some of which they are very destructive. They all assume a spiral position in repose or when alarmed; the head being placed in the centre. Prior to the time of Latreille, this entire division was included under the genus lulus, Linn. But the French naturalist restricted the term to the cylindrical species, and formed of the others his genera Glomeris, Polydesrnus, Polyxenus. Various species are described by Dr Leach, in a paper which stands in need of revision.^[8. Linn. Trans, xi. 377- ] We have here figured I. sabulosus, a common European species, Plate CCXXXIX. fig. 3. A monstrous Myriapod is mentioned by Ulloa as inhabiting the district of Carthagena.^[9. Voyage, vol. i. p. 61. ] ’ He describes it (if his terms have not been mistranslated) as sometimes extending a yard in length, and measuring five inches across. Here there is no doubt some gross exaggeration. He adds that its bite is mortal, if a∙ timely remedy be not applied. From its cylindrical form it has been regarded as an lulus.^[10. Kirby and Spence’s Introduction to Entomology, vol. i. p. 128. ' ] Genus Polydesmus, Lat. Body linear, the segments compressed on the under surface, with projecting ridges on the upper, somewhat in the form of transverse oblong scales.

The species of this genus, of which our Iulus complanatus, Linn, may be regarded as the type (Plate CCXXXIX. fig. 2), dwell under stones in dampish places. They assume the spiral form when touched, and feed both on animal and vegetable matters in a state of decomposition.

Certain other species, of which the eyes are obvious, form the genus Craspedosoma of Dr Leach.

Genus Polyxenus, Lat. Body soft, membranous, terminated by a tuft of lengthened scales.

The only species of which we have any knowledge is the Pol. lagurus, Lat. (Plate CCXXXIX. fig. 5), regarded as a scolopendra by the generality of systematic authors, and described by Degeer under the name of Iule a queue en pinceau. ^[11. Mémoires, t. vii. pl. 36. ] It is a very small creature, of rather singular aspect. Our magnified representation just referred to will save the necessity of descriptive details. Its early organization is less complicated than that of the adult state; that is, the young consist of fewer segments and a less number of legs. We know little of its natural habits. It occurs in the clefts of walls, and beneath the bark of old trees.

Order II.—CHILOPODA. Lat.

This division of the Myriapoda bears nearly the same relation to the unrestricted genus Scolopendra of Linnaeus, [7:15:654] as the preceding does to the genus lulus of the Swedish naturalist. The antennae become slender towards the extremity, and are composed of fourteen articulations and upwards. The mouth is composed of two mandibles, each furnished with a small palpiform appendage, and exhibiting in their centre the appearance of a joining, and ending in a spoon-shaped termination, with toothed edges. The labium is quadriful, with the two lateral divisions larger than the others, transversely ringed, and resembling the membranous feet of caterpillars. This labium is analogous to the lower lip of the chilognathous kinds, which represents in Latreille’s opinion the tongue of the crustaceous tribes, but possesses also the functions of maxillae. It is what Savigny names the first auxiliary lip. Besides these parts, there are two palpi or minute feet, united at the base, and unguiculated at the point; a second labium (seconde lèvre auxiliare of Savigny^[12. This piece is not attached to the head, but to the anterior extremity of the first semi-segment. The two hooked feet form by the union and dilatation of their first article a plate in the form of a labium or mentum, and the same semi-segment bears the two first ordinary feet, (Règne Animal, iv. 336.) ]), formed by a second pair of feet dilated and joined at their origin, and terminated by a strong hook, moveable, and pierced at the extremity, for the transmission of a venomous or acrid liquid.

The body of these unseemly creatures is depressed and membranous. Each ring or segment is covered by a coriaceous plate, and usually bears only a single pair of legs; and the terminal segment is generally thrown backwards, and elongated into a kind of tail. The organs of respiration are composed, either in whole or in part, of tubular tracheae. The sexual parts are interior, and placed at the posterior extremity of the body, as in the generality of insects properly so called. The stigmata are more obvious than in the preceding family, and are either lateral or dorsal.

The species of this division are of much more nimble habits than those of the preceding; and the peculiar mode in which the limbs act produces an undulating lateral motion. They are of carnivorous habits, and, avoiding strong light, usually conceal themselves under stones or old timber, beneath the bark of trees, &c. They are held in some dread by the inhabitants of tropical countries, where they attain a great size, and are consequently capable of inflicting dangerous wounds. But the majority of travellers seem agreed that, although the bite is more painful than that of a scorpion, it is never attended by fatal consequences. In more northern countries they are quite harmless, though disliked in consequence of their repulsive aspect. Our common centipede (Scolopendra forficata of Linn.) so frequent in this country under stones, may be mentioned as a familiar example. Lecuwenhoeck, the great Dutch microscopical observer, has described the perforation of the hooks, through which the poison is supposed to flow.

This order (which corresponds to the Syngnatha of Latreille’s earlier works, the title adhered to by Dr Leach) is divided into the following genera.

The first two have only fifteen pair of legs; and their bodies, when viewed from above, seem to present fewer segments than when examined from below.

Genus Scutigera, Lamarck.^[13. Latreille and others have adopted Lamarck’s designation, although the title of Ccrmatia had at a prior period been assigned to tins generic group by liliger. See Rossi’s Fauna Etrusea, t. ii. p. 299. ] Body covered by eight plates or shields, beneath each of which are two pneumatic pouches or vesicular tracheae, which receive the air, and communicate with lateral and inferior tracheae of a tubular form. The under surface is divided into fifteen semi-segments, each bearing a pair of feet terminated by an extremely long, slender, and minutely articulated tarsus. The terminal legs are long, and seem to increase in extent from the foremost to the hindmost pair. The eyes are comparatively large and reticulated. The antennae are very long and slender, and the palpi projecting and spinous.

The species keep themselves concealed during the day in barns, or the unfrequented parts of houses, lying between old planks, or sometimes under stones. They are seen at night running on the outside walls with great velocity, feeding on onisci, and various insects. They seem to pierce their prey with their mouth-hooks, and infuse into them a poisonous fluid, which immediately deprives them of life. These Myriapodes make their appearance in great numbers, chiefly in rainy weather. According to liliger, they are greatly dreaded by the inhabitants of Hungary. The best known European species is the & araneoides (Plate CCXXXIX. fig. 4). It is the Scolopendra coleoptrata of Linn, and Fab. Pallas asserts that it was taken by a friend of his among some fuci in the sea;^[14. Spicilegia Zοοlogica, fascic. 9, tab. 4, fig. 16. ] but as all analogy is against its natural occurrence in such a locality, we may infer that it had fallen accidentally from the timbers of a vessel.

Genus Lithobius, Leach. Body divided into an equal number of segments both above and below, each bearing a pair of legs. The dorsal plates are alternately long and short. The stigmatic openings are lateral.

We have figured our most common species, L.forficata (Plate CCXXXIX. fig. 6), a familiarly-known Linnaean scolopendra, as an example of the modern genus. It occurs almost everywhere, throughout the summer season, under stones. The anatomical structure of the genus has been described by Μ. Leon Dufour.^[15. < Annales des Sciences.Nat. II. 81. ]

The remaining generic groups of this order have at least twenty-one pair of legs, and the segments of the body are of nearly equal size, and of similar number, both above and below.

In the genus Scolopendra, properly so called, there are eight distinct eyes, four on each side, and the basal joint of the terminal legs is armed with small spines. We have no British species, but the south of Europe produces Scol. cingulata, which presents almost as formidable an aspect as some of the exotic kinds. The great foreign species (one of which sometimes measures above a foot in length) have been as yet but ill defined, several kinds being no doubt described under the name of Scol. mersitans, a native of South America (Plate CCXXXIX. fig. 9). A monstrous species, called Scol. Plumicri, is figured in Lister’s Journey to Paris, and appears to be also represented in Seba’s Thesaurus, under the name of Millepeda major eχ Nova Hispana. India, and the great eastern islands, produce some very large species; and scolopendrae of alarming size likewise occur on the African continent. The bite of these creatures is said to be dangerous;^[16. Bulletin de la Soc. Phil. January 1824, p. 24. ] but it seems that the poison of the wound is allayed by the use of ammonia. Μ. Àmoreux is of opinion that no poisonous power is possessed by any of the European species.^[17. nsect , ν enim , p , ∏. ] The whole are carnivorous and voracious, and, all things considered, they may be regarded as among the ugliest of creeping things. Nevertheless they are not without their advantage to the human race. “I have seen Indian children[7:15:655],” says Humboldt, “of the tribe of the Chuymas, draw-out from the earth and eat millepedes or scolopendrae, eighteen inches long and seven lines broad.”^[18. Personal Narrative, vol. ii. p. 205. ]

Other species, in which the eyes are obliterated or inconspicuous, and the basal joint of the last pair of legs is free from spines, form the genus Cryptops of Dr Leach.^[19. Zoological Miscellany, vol. iii. ] He has described two English species, and nobody appears to have since found any other elsewhere.

Some still more slender kinds, of which the antennae have only fourteen joints, but the legs are so numerous as sometimes to amount to nearly 300, compose the genus . Geophilus of Dr Leach. They are remarkable for their extreme tenuity, and at least one British species is at times beautifully phosphoric. We know not, however, whether it is identical with the Scol. electrica figured by Frisch, and described by Geoffroy.^[20. Histoire des Insectes, t. ii. p. 676, η. 5. ] Dr Leach has described the indigenous species.^[21. I-inn. Trans, xi. 384. ] They are destructive to fruit and vegetables. (τ.)