The subjoined wood-cut
represents a characteristic Chambered Shell of the Carboniferous age.
Goniatites is the scientific name of these later forms. If we had looked
for them in the Devonian period, we should have found many with looser
coils than these, and some only slightly curved in the shape of a horn.
These, as well as the perfectly straight forms, still exist in the coal
period, but the Goniatites with close whorls are the more numerous and
more characteristic.
[Illustration]
The Articulates have gained their missing class since the close of the
Devonian period, for Insects have come in, and that division of the
Animal Kingdom is therefore complete, and represented by three classes,
as it is at present. Of the Worms little can be said; their traces are
found as before, but they are very imperfectly preserved. There are
still Trilobites, but they are very few in number, and other groups of
Crustacea have been added.
One of the most prominent of these new types bears a striking
resemblance to the Horse-Shoe Crab of present times.
[Illustration]
[Illustration]
I here present one of our common Horse-Shoe Crabs above one of these
old-world Crustaceans, and it will be seen, that, while the latter
preserves some of the Trilobitic characters, such as the marked
articulations on the posterior part of the body and their division into
three lobes, yet in the prominence of its anterior shield, its more
elongated form, and tapering extremity, it resembles its modern
representative.
Pages:
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259