552 MANUAL OF NATURAL HISTORY. 



The crustaceans of this group comprise several 

 genera of the Trilobite family, as Galymene, 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 

 siphuncle ; the Gamer ocer as, with the siphuncle 

 lateral ; the discoidal Glymenia, with the siphuncle 

 internal ; the Aturia y with a large funnel-shaped 

 siphuncle ; and the curved, compressed, Phragmo- 

 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 Gyrtoceras ; 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 N~autilidce, 

 and among them the curious Lituites, with the last 

 chamber produced, besides Aploceras, Gomphoceras, 

 Actinoceras, and other extinct genera. The gas- 

 teropodous tribes are represented by Pleurotomaria, 

 Euomphalus, Bellerophon, Nerita, Natica, Megalo- 

 don, Galceola, 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 

 Gyathophyllum, the net-like Fenestella, and the 

 elegant chain-coral Gatenipora. 



