--_Atrypa reticularis_. Upper Silurian
and Devonian of Europe and America. (After Billings.)]
The _Brachiopods_ still continue to be represented in great force
through all the Devonian deposits, though not occurring in the
true Old Red Sandstone. Besides such old types as _Orthis,
Strophomena, Lingula, Athyris_, and _Rhynchonella_, we find some
entirely new ones; whilst various types which only commenced their
existence in the Upper Silurian, now undergo a great expansion
and development. This last is especially the case with the two
families of the _Spiriferidoe_ and the _Produclidoe_. The
_Spirifers_, in particular, are especially characteristic of
the Devonian, both in the Old and New Worlds--some of the most
typical forms, such as _Spirifera mucronata_ (fig. 96), having
the shell "winged," or with the lateral angles prolonged to such
an extent as to have earned for them the popular name of
"fossil-butterflies." The closely-allied _Spirifera disjunda_
occurs in Britain, France, Spain, Belgium, Germany, Russia, and
China. The family of the _Productidoe_ commenced to exist in the
Upper Silurian, in the genus _Chonetes_, and we shall hereafter
find it culminating in the Carboniferous in many forms of the great
genus _Producta_[17] itself. In the Devonian period, there is an
intermediate state of things, the genus _Chonetes_ being continued
in new and varied types, and the Carboniferous _Produdoe_ being
represented by many forms of the allied group _Productella_.
Pages:
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239