Favosites polymorpha, Goldf., S. Devon. From a polished specimen.
a. portion of the same, magnified to show the pores.
The Cyathophyllum cæspitosum ([fig. 402.]) and Porites pyriformis ([fig. 424.] [p. 356.]) are more peculiarly characteristic of the Devonian rocks.
In regard to the shells, all the brachiopodous genera, such as Terebratula, Orthis, Spirifer, Atrypa, and Productus, which are found in the Mountain limestone, occur, together with those of the Silurian system, except the Pentamerus. Some forms, however, seem exclusively Devonian, as for example, Calceola sandalina ([fig. 403.]) and Strygocephalus Burtini ([fig. 404.]), which have been met with both in the Eifel, in Germany, and in Devonshire, in the very lowest Devonian beds.
Fig. 402.
- a. Cyathophyllum cæspitosum, Goldf., Plymouth.
- b. a terminal star.
- c. vertical section exhibiting transverse plates, and part of another branch.
Among the peculiar lamellibranchiate bivalves, also common to Devonshire and the Eifel, we find Megalodon cucullatus ([fig. 405.]). Several spiral univalves are abundant, among which are many species of Pleurotomaria and Euomphalus. Among the Cephalopoda we find Bellerophon and Orthoceras, as in the Silurian and Carboniferous groups, and Goniatite and Cyrtoceras, as in the Carboniferous. In some of the upper Devonian beds, a shell, resembling a flattened Goniatite, occurs, called Clymenia, by Munster (Endosiphonites, Ansted.[347-A]).