MUSEUM OF COMPARATIVE ZOOLOGY. 79 



Coroniceras Brookei Hyatt. 



Amm. Brookei Sow., Min. Concli., v. 2, p. 203, pi. 190. 

 Loc. Lyme Regis ; Coll. B. M. Wright. 



Asterocera3* Hyatt. 

 Keel well defined, but varies from prominent and narrow to depressed 

 and broad. Channels obscure to deep and well defined. Pilae smooth, de- 

 pressed ; often bent on the sides, and appear in the young as lateral folds 

 or large tubercles. Sides in some species not enveloped; in others, cov- 

 ered to fully one half of their breadth. Ventral lobes very deep. Lat- 

 eral lobes very shallow. Superior and first auxiliary cells short and broad 

 Inferior lateral cell very prominent. 



Asteroceras tenue Hyatt. 



Loc. Semur, Aargau, Aalen, and Goppingen ; Coll. Prof. Bronn and 

 Dr. Krantz. 



Abdomen narrow. Dorsal region broad, angular at its junction with 

 the sides. Keel narrow and prominent ; channels large. Superior lateral 

 cell almost obsolete. Inferior lateral unequally divided. 



Asteroceras trigonatum Hyatt. 

 Amm. Brookei Ziet., Verst. Wiirt., p. 3G, pi. 27, fig. 2. 

 Loc. Aalen ; Coll. Dr. Krantz. 



Transverse section of the whorl obtusely triangular. Pilaa prominent in- 

 ternally, decreasing gradually externally. Tubercles are not constantly 

 found in the adult as in Amm. Brookei, and it differs, also, from the latter in 

 the narrowness of the abdomen, the greater proportional breadth of the 

 dorsal region, and the decided inclination of the sides of the adult whorls. 



Asteroceras obtusum Hyatt. 



Amm. obtusus Sow., Min. Conch., v. 2, p. 151, pi. 167. 



Amm. redcarensis Young and Bird, Geol. York., pi. 14, fig. 15. 



Amm. obtusus D'Orb., Terr. Jurass., p. 191, pi. 44. 



A?)im. slellaris D'Orb., Terr. Jurass., p. 191, pi. 45. 



Amm. Turneri Ziet., Verst. Wiirt., p. 15, pi. 11, fig. 5. 



Loc. Lyme Regis, Whitby, Robin Hood's Bay, Semur, Boll, Balingen, 

 Bempfiingen, Stuttgart, and Adnet; Coll. L. Agassiz, Robert Damon, 

 Marder, B. M. Wright, L. de Koninck, Dr. Krantz, M. Boucault, and Mus. 

 of Stuttgart. 



The identification of Zieten's Turneri with Amm. obtusus Sow., was 

 made with authentic specimens from Zieten's former collection sent to this 

 Museum by the Museum of Stuttgart, and although the characteristics are 



* Aottjp, a star. 



