98 BULLETIN OF THE 



greater number of whorls in specimens of the same size. The sides of the 

 whorls are also less gibbous than in P. robustum, and auxiliary cells differ- 

 ently formed, being comparatively but slightly indented by the minor lobes, 

 and the inferior lateral cell inclined toward the umbilicus, instead of being 

 straight. 



Phymatoceras robustum Hyatt. 



Loe. Plateau de Larzac, Milhaud, and Semur; Coll. Dr. Krantz, L. de 

 Koninck, and M. Boueault. 



Ammatoceras. 



Amraatoceras insigne Hyatt. 



Amm. insignia Schub., Ziet., Verst. Wiirt., p. 20, pi. 15, fig. 2. 

 Amm. insignis D'Orb., Terr. Jurass., Ceph., p. 347, pi. 112. 

 Amm. insignis Quens'dt, Die Ceph., p. 280, pi. 40, figs. 4, 5. 

 Loc. Gundershoien (Bas-llhin) ; Coll. M. Boueault. 



Ammatoceras variabile Hyatt. 



Amm. variabilis D'Orb., Terr. Jurass., Ceph., p. 350, pi. 113. 

 Loc. Laumiere, Salins, Plateau de Larzac, St. Julien de Croix in Saone 

 et Loire, Besancon, Evrecy bei Caen, Boll, and Balingen; Coll. Mus. of 

 Stuttgart, L. de Koninck, Dr. Krantz, and M. Boueault. 



Pelecoceras* Hyatt. 

 Having but one species of this genus, it would be exceedingly hazardous 

 to give the generic characters. They will, however, probably be found to 

 be distinguished by the peculiarly pointed aspect, shallowness and breadth 

 of the lobes and cells; the limits of the envelopment, which last is greater 

 than in other genera of this family ; the acute form of the back, and the 

 breadth of the whorls. 



Pelecoceras attenuatum Hyatt. 



Loe. Plateau de Larzac, Milhaud, and Besancon ; Coll. Dr. Krantz and 

 L. de Koninck. 



Abdomen acute. Sides very broad and flat. Envelopment covers over 

 one half the side of each internal whorl. Pilas are curved forward on the 

 abdomen. The young have no channels, and the development does not 

 differ from Amm. variabilis or Amm. insignis, except in the size of the 

 young, the whorls of these not being proportionately so large or broad. 

 All the lobes and cells are broad and shallow, especially the pointed ab- 

 dominal and the serrated auxiliary cells. 



* IltXfKuj, an axe. 



