DEVONIAN PERIOD. 523 



nus, &c.), along with Pentremites ; whilst Cystideans are stated 

 to make their last appearance here. 



The Articulates are represented by numerous Crustaceans, 

 and by a few insects the latter being the first of their class. 

 The Crustaceans are abundant, the chief forms being Trilobites 

 (Phaeops, Bronteus, Homalonotus, &c.), large Eurypterids (Ptery- 

 gotus, Stylonurus, Eurypterus, &c), and Ostracodes (Entomis, 

 Leper ditia, Beyrichia, &tc.) The bivalved carapaces of the last 

 mentioned of these groups are very abundant in certain De- 

 vonian beds, and the so-called " Cypridinen-schiefer " of the 

 Devonian series of Germany derives its name from the occur- 

 rence in it of vast numbers of the little Entomis ( Cypridina] 

 serrato-striata. In certain Devonian beds, also, the remains of 

 the Crustacean genus Estheria are very abundant. The Devo- 

 nian Insects appear on the whole to have the closest affinity 

 with certain of the existing Neuroptera or Pseudo-neuroptera. 



The Mollusca are largely represented in Devonian time, and 

 the Brachiopods are especially abundant. The most charac- 

 teristic forms are those of the genera Stringocephalus (fig. 144) 

 and {Incites, along with numerous broad-winged Spirifers (such 

 as S. mucronata, fig. 148). Lamellibranchs (such as Megalo- 

 don and Pterinea), Gasteropods (Macrocheihis, Trochus, Pleuro- 

 tomaria, &c.), and Pteropods (Conularia) are well represented 

 in the Devonian Rocks. As in the case of the Silurian period, 

 no certain traces of the existence of Dibranchiate Cephalo- 

 pods have been as yet detected in the Devonian. The Tetra- 

 branchiate Cephalopods, however, are known by true Nautili 

 and Orthocerata, and by the genus Clymenia. The family of 

 the Ammonitidce is also represented by the genera Goniatites 

 and Bactrites. 



The sub-kingdom of the Vertebrata is still represented by 

 fishes only ; but these are so abundant that the Devonian 

 period has been commonly called the " Age of Fishes." Most 

 of the Devonian Fishes belong to the order of the Ganoids, 

 and especially to the two groups of the Crossopterygida and 

 Ostracostei. The genera Cephalaspis, Pteraspis, Pterichthys, 

 and Coccosteus, do not survive this period, and there are many 

 other peculiar Lepidoganoids as well. Besides Ganoids, nu- 

 merous remains of Elasmobranchii have been detected, these 

 being referable both to the Cestraphori and to the Selachii. It 

 is probable, also, that some of the Devonian fishes are rightly 

 referable to the order Dipnoi, finding their nearest living 

 allies in the Mud-fishes of South America and Africa, and the' 

 Barramunda of Australia. 



