380 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



The septa are ceratitic, but the saddles are also slightly denticulated. 

 The external lobe is divided by a short siphonal saddle ; the first lateral is 

 large and slightly digitate ; the second lateral is smaller and simpler ; this is 

 followed by a similar but smaller third lateral. The true auxiliaries consist 

 only of denticulations below the auxiliary saddle. The septa are not like 

 those of Ceratites (Gytnnotoceras) blakei Gabb, with which species Gabb 

 united it. 



The young shells are more robust, evolute, and have rougher sculpture. 



This species was erroneously assigned by Hyatt to his 

 genus Gymnotoceras, but it agrees in all respects with Bey- 

 richites. It is not impossible that this genus may belong to 

 the Ceratitidae. 



Horizon and locality. Middle Trias, Daonella beds, 

 New Pass, Desatoya Mountains, Nevada, and in the West 

 Humboldt Range, Nevada, in Buena Vista Canyon, and on 

 the divide between Troy Canyon and the south fork of 

 American Canyon. The figured specimen was collected 

 by the writer at the latter locality, associated with Anolcites 

 whitneyi, Acrochordiceras hyatti, Gymnotoceras blakei, and 

 many other characteristic Middle Triassic species. 



Genus Eutomoceras Hyatt. 



1877. Eutomoceras, Hyatt, U. S. Geol. Expl. Fortieth Parallel, Vol. IV, 

 p. 126. 



Type, Eutomoceras laicbei Meek, U. S. Geol. Expl. Fortieth Parallel, Vol. 

 IV, p. 126, pi. X, figs. 8, 8 a. 



Involute, discoidal, laterally compressed, with flattened sides, narrow ven- 

 ter, distinct umbilical shoulders, and narrow acute venter surmounted by a 

 sharp solid keel without marginal furrows. Surface ornamented with radial 

 dichotomous ribs that branch out from knots on the umbilical shoulders, 

 curve upwards on the sides, and bend sharply forward on the shoulders to 

 the keel. Also small knots occur on the lateral ribs at irregular intervals, 

 not arranged in spiral lines. 



The septa are ceratitic, consisting of a divided ventral lobe, two principal 

 laterals, and several smaller auxiliaries. The saddles are all rounded and 

 entire, while the lobes are distinctly serrated. Internal septa and length of 

 body-chamber unknown. 



This genus greatly resembles Hungarites Mojsisovics, 

 and differs from that group chiefly in the distinct sickle- 

 shaped ribs, the irregular knots, and the extremely high 

 keel. It has very probably developed out of Hungarites, 

 for its young stages are almost identical with mature forms 



