76 BULLETIN OF THE 



Sides convex ; pilae depressed. The pilae and tbe form of the whorl in 

 the young, greatly resemble those of adult raricoslalus, but in the adult 

 they closely resemble those of the adult shell of 0. Johnstoni. 



Septa unknown. 



Ophioceras tortile Hyatt. 



Amm. tordlis D'Orb., Terr. Jurassique, I., p. 201, pi. 49. 

 Loc. Seinur ; Coll. Boucault. 



Ophioceras deciduum Hyatt. 



Amm. Nodotianus Ilauer, Cepli. d. Lias d. Nordostlichen Alpen, p. 24, 

 pi. G, figs. 1 -3. 



Loc. Whitby; Coll. Dr. Krantz. 



Amm. Nodotianus D'Orb. is probably generically different, since it has 

 a more acute abdomen. 



Discoceras * Agassiz. 



Abdomen keeled and channelled. Loth characters are constant, al- 

 though the channels are sometimes nearly obsolete. Pilae smooth. Geni- 

 cuhe curved forwards. Umbilicus open. Sides flattened, exposed. Ab- 

 domen depressed. Abdominal lobe deep and narrow. Superior lateral, 

 and inferior lateral, narrow and irregularly pointed with minor lobes. 



Superior lateral cell equally divided. Inferior lateral, unequally di- 

 vided. First auxiliary cell well developed, and nearly as long as the 

 inferior lateral. 



Discoceras? laqueus Hvatt. 



Amm. laqueus Quens'dt, Der Jura, p. 43, pi. 3, fig. 5. 



Loc. Nellingen, Wiirtemberg; Coll. Mus. of Stuttgart. 



The abdomen of the specimen examined is so obscured by its matrix of 

 limestone, that the reference of the species to this genus must be considered 

 doubtful. 



Discoceras ophioides Hyatt. 



Ammonites ophioides D'Orb., Terr. Jurassique, p. 241, pi. CI. 

 Loc. Semur ; Coll. Boucault. 



Discoceras carusense Hyatt. 



A ikiii. carusensis D'Orb., Terr. Jurassique, I., p. 284, pi. 8, figs. 3-6. 

 A mm. spiratissimus Ilauer, Ceph. d. Lias d. Nordostlichen Alpen, p. IS, 

 pi. 3, li^'s. 1 -3. 



Loc. Semur, Balingcn; Coll. Boucault, L. de Koninck, and Prof. Bronn. 



* AiWoj, a quoit. 



