MUSEUM OF COMPARATIVE ZOOLOGY. 91 



Amm. paradoxus Stahl, Zlet., Verst. Wiirt., p. 15, pi. 11, fig. 6. 



Loc. Plateau de Larzac, Ileiningcn, Boll, Lutzude bei Hanover, Semur, 

 Gbppingen, Ofterfeld bei Goslar, and Pliensbach ; Coll. Mus. of Stuttgart, 

 Dr. Krantz, L. de Koninck, Prof. Bronn, L. Agassiz, and Boucault. 



Amaltheus margaritatus De Mont. 



Amaltheus margaritatus De Montfort, Conch. Sys., p. 91. 



Amm. acutus Sow., Min. Conch., v. 1, p. 51, pi. 17, fig. 1. 



Naut. rotula Rein., Naut. et Argo., p. 59, pi. 1. fig. 5. 



Amm. Stokesi Sow., Min. Conch., v. 2, p. 205, pi. 191, figs. 9, 10. 



Amm. clevelandicus Phil. Geol. York., pi. 14, fig. 6. 



Amm. amaltheus Ziet., Verst. Wiirt., p. 4, pi. 4, fig. 1. 



Amm. margaritatus D'Orb., Terr. Jurass., I., p. 240, pi. 6 7. 



Loc. Whitby, Avallon, Semur, Milhaud (Dep. de l'Aveyron), Bas-Rhin, 

 Lutzude bei Hanover, Eislingen, Rezingen, Wasseralfingen, Gundershofen, 

 Miihlhausen, Boll, Ubstadt bei Bruchsal, Falkenhagen in Lippe, Balingen, 

 and Gbppingen ; Coll. Mus. of Stuttgart, L. de Koninck, Prof. Bronn, 

 L. Agassiz, and Boucault. 



Amaltheus praestabilis Htatt. 



Amm. amaltheus nudus Quens'dt, Der Jura, p. 16 7, pi. 20, fig. 4. 



Amm. amaltheus nudus Quens'dt, Die Ceph., p. 94. 



Loc. Robin Hood's Bay, Scarborough, Y\ hitby, Mende in Lozere, Venarey 

 pres Semur, Milhaud, St. Cyr pies de Lyon, Metzingen, Lutzude bei Hano- 

 ver, Balingen, Geislingen, and Gbppingen ; Coll. Mus. of Stuttgart, Dr. 

 Krantz, L. de Koninck, M. Boucault, Prof. Bronn, and L. Agassiz. 



CYCLOCERATID-E. 



This family is remarkable for containing species which on the one side 

 ally it with the Liparoceratidce, and on the other with the higher Hildocera- 

 tidcE. There is, however, a general agreement in the development and in 

 the septal characteristics, which unite them in one family. The form is 

 much more compressed laterally than in the Liparoceratidce and the tuber- 

 culations of the pilas separate them from the Hildoceratida;. The young 

 of Tropidoceras Actceon resemble the adults of Cycloceras Vahlani. and the 

 young of the last in their turn are like the adults of Platypleuroceras latce- 

 costa ; thus all three genera are closely connected by development. The 

 abdominal lobe is of about the same depth as the superior lateral ; the latter 

 is unequally divided into three minor lobes of variable length, and there is 

 only one auxiliary lobe exposed to view on the side. Superior lateral cell is 

 generally equally divided, and of great breadth. Inferior lateral, narrower 

 and more prominent. 



