The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1867-02-21


the flesh is white, and arranged in large masses
ON the sides of the backbone il the organs of
respiration are gills instead of lungs: IL the
organs of inhalation exhibit heart which has
only single sack from which the blood Is pro-
PEELED to all parts of the body, and another
sack to receive the blood which comes from all
parts of the body, instead of the complicated
circulation which we find in birds and in MAN.
malia--we say that we have here one mode of
execution of the plan of structure, which iusti-
fies us in considering fishes as a natural class
II, ON the contrary, we have animals which
have warm blood, which breathe through the
lungs, which have double circulation. tbe
body of which, instead of being covered with
scales, is covered with feathers, if these ami
mails, in bringing forth their young lay eggs
upon which they sit, producing young which
they rear, we have indications of another mode
of execution of that plan of vertebrates: and we
consider ourselves justified in calling birds n
class in the animal kingdom and so on. Now.
among mollusks, we have three classes. one of
which is particularly characterized by the
manner in which the parts are arranged on
the two sides OF the body, in broad flappers, or
broad curtains hanging on the sides of the
axis, and generally protected by hard shells
that are double that is, one on each side: and
that class embraces all the so-called bivalve
shells. Of this class, the Amazon contains a
considerable variety, and so do all our fresh
NdlcIS, OuI rivers anu ldkeSs
VARIETY OF MoLLUsKs.
In the ocean there are numerous forms,
but no one of these bvalve shells living upon
the land or in the atmosphere, or that can
sustain itself outside of water. Then we have
another class among these mollusks which
| embrace all those the body of which has respi-
ratOry organs only on one side of the body
namely, the body of which is more or less
| twisted, frequently coiled up in spiral, and
i'll which the anterior end Of the body is pro-
vided with appendages looking something like
homs-tentacles frequently, at the end of
which are eyes, like our snals They cOnsti-
tute a second class. OF this class of snails we
| find quite a variety in the fresh water in the
Amazon, and in still greater variety upon
| land, living upon trees and decaying wood, or
| upon the SOIL burrOwing in the earth during
the dry season. So that of the three classes
of mollusks which exist all over the world
we have representatives of two in the fresh
water of the Amazon, and of one of those two
we find also representatives on land. There is
a curious feature among these fresh-water
bivalve shells to which l will here allude-
! their strange resemblance to marine shells,
notwithstanding the difference of their internal
! structure.
| THE AMERICAN BIvALvEs.
You all know how numerous fresh-water
! muscles are III our waters, and how great is
| the diversity of the fresh-water shells in the
| Western waters. The Ohio and its tributaries,
the Tennessee and the Cumberland rivers, and
| the rivers that empty into the Gulf of Mexico,
and all the Southern rivers, TEEN with a
variety of bivalve shells, all of which have the
same internal structure, consisting of this ill
| Illustrating by drawing the parts as describeO;
| that the middle axis may be protruded in the
shape of heshy foot with which the animals
creep on the ground or in the wood. At the
sides are two tappers, which surround the
mouth, to aid in introducing food into
the alimentary cavity. Then, there are
two gills hanging right and left. Inside
here is a sack which contains the organs; and
here is a large feshy mass which extends
across the body, and here another; so that
upon q transverse section of these animals we
| would see one valve turning this way and the
other that way. And here is one of those
bundles extending from one valve to another,
so as to bring them together; and here is
another. Now these fresh water shells of
ours vary in external appearance greatly.
| Some are smooth and have a thin shell, and
have an oviate form. Others are elongated in
| this way; others are more triangular; others
! have tubercles on their surface; others have
| spines projecting from the surface; others have
rows of ribs thus, and others rows of ribs in
this manner. But while the different species
thus differ in their external appearance, their
| internal structure is everywhere We same.
| PEcULIARITIEs.
The species of the Amazon have another
curious feature-that they are not only iden-
| tical in structure with our own, and identical
! among themselves in structure, but their eX-
| ternal forms are the marine shells, which have
| a totally different structure. Those among you
| who know the shell of the razor-fish called the
razor-shell Ca very slender and straight shell Of
| this form) will be surprised to hear that there
| are fresh-water shells of that form in the
| Amazon, which, far from having anything in
| their internal structure which resembles the
! solens Gas this is called by naturalists), have
| all the internal structure of our common fresh
water muscles. There are others which have
| the external appearance of the mother-of-pearl
| bivalve she'll exhibiting the external appear
ance of that group. third variety exhibits
| the peculiarities of our area, having transverse
waves alternating with burrows, such as are
only known in the family of the marine area,
| and vet found in some of these fresh-water
| shells. What does that mean? 1t is difficult
TO say why there should be, as it were, a
| reminiscence of the sea among animals of the
fresh waters, superimpOsed upon a structure
which has no similarity to the structure Of
! these marine shells.
MYSTERIES OF THE CREATIVE POWER.
can only see in this the working of mind,
which combines elements diversified among
| themselves, and hardly any indication OF the
| transformation Of one type into the other
| But, without expressing decided opinion
| about it, let me tell you that those are the
| facts upon which naturalists agree, and i'll
| consequence of which they present such
various opinions, such conflicting views The
naturalist who recognizes only this similarity