CEPHALOPODA— AMMONOIDEA. 155 



246. M. (Koninckites) mushbachanum White. (Fig. 1403,7, ^.) 



Triassic. 



Sides flat ; umbilical angle abrupt ; umbilicus moderate, venter 

 abruptly and narrowly rounded; surface with faint, low folds 

 spreading from umbilical margin; septa with rounded, entire sad- 

 dles ; lobes strongly serrate ; siphonal saddle broad. 



Lower Triassic of southeastern Idaho, and Inyo County of 

 California. 



247. M. (Gyronites) aplanatum White. (Fig. 1403, /-».) Triassic. 

 Sides flat; whorls subquadrangular, higher than wide; venter 



flat with angular margins; umbilicus large; umbilical shoulder 

 abrupt ; surface with low, indistinct and broad folds ; suture with 

 rounded, entire saddles and partly serrate, partly entire lobes. 



Meekoceras beds (Lower Triassic) of southeastern Idaho, and 

 Inyo Range, California. 



CIII. EuTOMOCERAS Hyatt. 

 Differs from Meekoceras in having a sharp, solid, ventral keel 

 without marginal furrows ; dichotomous ribs branch from tuber- 

 cles at umbilical shoulders and carry other tubercles at irregular 

 mtervals ; suture with divided ventral and two principal lateral 

 lobes, and several smaller auxiliaries, all serrated ; saddles entire, 

 rounded. Triassic. 



248. E. laubei Meek. Triassic. 

 Ribs in bundles of twos or threes on umbilical tubercle ; height 



of adult body whorl one half total diameter of shell. (Type of 

 genus.) 



Middle Triassic, West Humboldt Range, Nevada. 



CIV. LONGOBARDITES Mojsisovics. 



Involute, discoidal, with closed umbilicus and acute venter; 

 surface smooth except for growth lines ; suture with rounded sad- 

 dles and serrate lobes, the third of which from venter is largest. 

 Triassic. 



249. L. nevadanus Hyatt and Smith. (Fig. 1404, a-c.) Triassic. 

 Height of body whorl more than half the diameter of shell ; all 



lobes goniatitic in early adolescent stage ; auxiliary lobes mostly 

 remain so in adult. 



Middle Triassic of Nevada. 



