552 MANUAL OF NATUKAL HISTORY. 



The crustaceans of this group comprise several 

 genera of the Trilobite family, as Calymene, Asa- 

 phus, Harpes, Homalonotus, and Brontes. 



Among the cephalopodic forms of molluscous ani- 

 mals, we find numerous genera of the family Cly- 

 menidce, as the straight Orthoceras, with central 

 siphuiicle ; the Cameroceras, with the siphuncle 

 lateral ; the discoidal Clymenia, with the siphuncle 

 internal ; the Aturia, with a large funnel-shaped 

 siphuncle ; and the curved, compressed, Pliragmo- 

 ceras. Among the cephalopods of this epoch, we 

 also observe several members of the family Ammo- 

 nitidce, with their shells spiral, straight, or variously 

 bent. Here we have the curved Cyrtoceras ; the 

 straight Stenoceras ; the nautiloid Gyroceras, with 

 the whorls disunited ; and the Goniatites, with dis- 

 coidal shell, and lobed sutures ; besides upwards of 

 one hundred and twelve fossil species of Nautilidce, 

 and among them the curious Lituites, with the last 

 chamber produced, besides Aploceras, Gomplioceras, 

 Actinoceras, and other extinct genera. The gas- 

 teropodous tribes are represented by Pleurotomaria, 

 Euomphalus, Bellerophon, Nerita, Natica, Megalo- 

 donj Calceola, and Strygocephalus ; and a little un- 

 known bivalve has been found in this formation in 

 the Orkneys. 



The zoophytic remains are numerous, among 

 which we may observe the beautiful honey -combed 

 Favosites and the starred Favistella, the cup-shaped 

 Cyathophyllum, the net-like Fenestella, and the 

 elegant chain-coral Catenipora. 



