42 



POPULAB CONCHOLOGY. 



Cyrtoceras. Goldfuss. (Campulites Desk.) — Shell 

 many-chamber ed, but in form resembling a curved horn, 

 never rolled up ; the partitions oblique, with simple edges ; 

 the siphuncle somewhat sub-dorsal, sometimes central, at 

 others near the under side ; the mouth usually oval, with the 

 front and back compressed together. — 36 species, fossil. 



Phragmoceras. Broderip. — Shell many-chambered ; 

 laterally compressed; curved, 

 but having no spiral part ; the 

 partitions simple, with a large 

 sub-ventral radiated siphuncle ; 

 the last chamber very large ; 

 mouth narrow, longitudinal, 

 wedge-shaped, of which the 

 hinder end extends into a 

 broad oblique sinus. — 8 species, 

 fossil. 



Gomphoceras. Munster 

 egg-shaped, many-cham- 

 bered, and enlarged in front 

 into the egg-shaped, almost 

 spindle-formed, last cham- 

 ber, which receives the en- 

 tire animal; the mouth 

 contracted in the middle, 

 almost triangular, formed 

 of three lobes; the parti- 

 tions oblique, numerous, 

 simple, with a small, al- 

 most central bead-shaped 

 siphuncle. — 10 species, fossil. 



Ortiioceras, Breyn. — Shell many-chambered, in 

 form of a more or loss gradually slender cone: the par- 



mm 



Phragmoceras ventricosum 



Shell straight, short, almost 



Gomphoceras ptjriformc 



