Memphis daily appeal. [volume] (Memphis, Tenn.) 1847-1886, 1867-02-24
THE AMAZON,
Its Aquatic Animals ASassiz's
FOurth Lecture.
nm the ny TrIhnne. Ial

!
population Of any extensive fresh water
basin has many points OF interest We
NAV, in the first place, view it in
reference to the structure of these
animals, rs compared with that Of
serial and terrestrial beings. We may
examine them with reference to their
1 geographical distribution as contrasted
| with those which inhabit the sea or the
land. We may also examine them with
reference to theiI variety, or the diver
sity which exists among them, under
apparently identical circumstances. This
/ last point is one Of peculiar interest,
because YOU will perceive that if exter-
nal circumstances have had deep
/ influence in bringing about the
variety Of living beings which we
! find everywhere on the surface of
/ the earth, We sheuld expect to
] find great similarity among animals liv-
] ing close together, under identical cir
/ cunlstances, shut out from the influences
| of the great changes which are constant
/ Iy taking place in the atmosphere, shut
| out from the great diversity of the bot
| toms which are found along the sea-
| shores, and circumscTibed within limits
very similar. Now, the Amazon, above
| all the rivers OF the earth, presents va
rietv Of organized beings which is
stupendous, which exceeds all concep-
! ton, and which was a matter Of
surprise even to me, who had devoted
my life chiefly to the study Of fishes. |
will. therefore, try to give you some idea
of this diversity. l regret only that /
cannot suddenly impart to you the in
( terest which ] have felt for long time
| in these animals. Unknown and unin-
! teresting in their ways, they have gem
| erally been neglected. Few naturallsts
have turned their attention TO Othem, end
l am afraid you will find my lecture
| rather monotOnous. Yet, If you VIII Tor
! a moment consider that Acknowledge
| of these beings has an important bearing
| on some OF the most important questions
which are now under discussion among
Daturallsts. hope yoU will follow me
/ in the details which / an about to sub
NIT To YOU. But first allow me 10 say
| few words concerning the structure OF
AQUATIC animals In the infancy OF our
| science, animals were classified, that Is,
were brought together in groups, ac-
c0rding to the conditions under which
thew are found In nRtUre. II you viii
turn over the works OF the great natural
/ ISIS Of the eleventh century, you will
find that their descriptions of the ami
mais then known are arranged under
but few heads, one embracing the
aouatic animals. another the terrestrial
or creeping animals, and the other the
n-rial or flying aRimals. But IN proper
ton as our information Of the structure
Of all these beines has been growing, 1t
has been found that these external influ-
epces do not so modify organized bUings
as 10 bring together In the same habi
tation those which have the closest re-
80, Han mud wa are lnnHnr ElIr-
prised now 10 find in the water animals
Of the most diversified classes, or to
find the same diversity among those
which either inhabit the land or
live in the air, il has been the
result Of modern investigation to dis
cover that animals, however numef-
Gus. however varied, are, after all, built
upou four plans Of structure only. Those
niaus are very simple, and may be rec
c0njled easily; and these systems may
he EXPRESSED by formulas 50 simple that
YOU will permit Ins Tor moment 10 call
your attention 10 that point. There are
animals which have all parts asranBeH
like rays around 9 central aHls-tnat y.
thev are radiated Ia strBGtHre; and q
figure like this draws u gtar-zhaped
character on the blsckbOard) may De
consideEsd as formula expressing those
HgcuiaTlLles o. sAuCtuAt' A7NPPo0N
that we c0Hsidef Eny organ, the
stomach for instances II @iii be iound
to have five pouches radlatinS IA
ivs different directions. sHppase that
we consider the nervous system-lt VIII
Ice found to consist OF five rings, five
sWellings, with the same directions as
the five pouches Of the stots;ach ; hve
rsys or threads having the same diseG-
ton, and may be at the ends Of the
threads there may lie eyes. The oVarles
will be arranged in the same manner,
with a bunch Of eggs here, buneh OF
eggs here, bunch OF eggs here; ana an-
other there. And all these parts are so
arranged Rrsuad a central axis; and IN
that axis we have Ghe mouth at the CEN
ter. SO these animals, ossing to this pc
cuIiarity of constitution, are jusuy cSlled
rsdiates Now, Of th0ae we do not fnd
any in the Amazon. AFe 90 not hnd
any in the fresh waters except one. the
simplest kind Of pOlyp, the fresh water
pOlvp, or bush pOlyy, a. it Is called TINS
IL the only fresh water specimen nt tlat
large family which is innumerabig IN
salt water, such as the Jelly fishes, star
fishes. and seR-urchins-in fact most OF
the animals that iBhAbit the sea, and
which have existed not only Of ali times
hut which are now common everywhere
in the ocean, bat which have no repre-
sentative on land, and but a few very
simple ones i'm the fresh waters of the
temperate zone. Another group, Ehich
are called mOllusks, embrace animals, the
body Of which Il symmetrical, the parts
of which are arranged around Two SIDES
OF a longitudinal aXiS, so that these AMI
mails have an anterior and a pOstefior
psrt-a psft that is above and part that
i below rigiit and left, which is not
the case with the rAdiates; for these ra-
dIstes may move in tins direction OF
either one OF thee rays-they have no
right and no loft for ~ yOu call gbt~
tie front, fhis may be the right and utts
left, bat II you call fliS front, ttiis -
right and this left, so that yo1 have u
introduce an arbitrary distinction, when
YOU hear described these fadiste ami
malls. with reference 10 Whinh - tio
r;st,t sud when Is the left side, which Is
the part that j. above, and which is the
part Glat Is below, Not so with the
mollusgs. They have inLsTnsl features
which determine their relation, their
symmetry, and fix the position Of then
parts in "a manner which enables US 10
distinguish the anterior OF head etfq from
the pnsterior or tail end, as well as tile
right and left, and above and below, 70
this group of animals belong all the
she'll -6shes-tHe Glams, oysters and the
ike. the snail and tue cattle fishes also.
Part 9f them are aquatic aniulGls, that
inbai,it the sea, part Of them are fresh
water fishes, aud part of them are ter
restrial animals. SO yoa seq here, we
have animals OF Gus and Toe satae
structure inhsbiting the different eie-
meRts. which were made in the infancy
Of our science, the foundation Of the clas-
| sificatioR Of the whole animal kingdom.
| or this type there are several classes,
| three classes, and to them / sbail refer
! presently, as we have a number Of rep
/ resentatiges Of them in the fresh water
animals Of the AmaZOn. Let me say
that the majority OF tllase which have
! two valves are either fresh water or ma
rine, the greater part, however, nlBFi2e,
and de iags number are fresh water or
those which hEve only one valve, and
are generally wousd 4p ~ spiral, we
have also a majority in tha sea, but
some In fresh water, and some on land. l3f
tbecuttle- fiSh class there are nonein fresh
water, none are terrestrial, but all Of
them are marine. And they have been
inhabitants OF our globe from the very
earliest periodz OF the earth's history
during which animals have lived upon
/ il. may represent the fOTFaria Of these
animals 10 this way illustrating on the
blackboard), the anterior end marked
by some prominent feature which indi-
Gates something of head. Not all,
however, have the ANTERIOR end very
! different from the posteriOr. 4 l0ngitg.
dinal axis, on the side Of which organs
are arranged For instance, in the oyster
there il 3 pair Of giils on each side, so
| that the respiratory organs are placed
on the right and on the leiti while
about the sides oi lie mouth are
those tat Appendages, With the aid Of