CEPHALOPODA— AMMONOIDEA. 193 



tinuously; intercalated ribs do not reach umbilicus; saddles of 

 suture broad. 



Horsetown of California. 



CXLVIII. SoNNERATiA Baylc. 

 Differs from Hoplites in the strong ribs which begin with weak 

 umbilical node and extend across the arched or carinated venter. 

 Comanchic. 



335. S. acuto-carinata (Shumard). Comanchic. 

 Strongly involute, sharply carinated; keel smooth, sharp; sides 



flat; 30-34 flexuous ribs on last whorl, alternating in length and 

 widening to within short distance of dorsal border where they 

 are again somewhat contracted; aperture elongate and cordate. 

 Fredericksburg of Texas, etc. ; also South America. 



336. S. stantoni Anderson. Comanchic. 

 Small (3.5 cm. zh); sides flattened and gently converging to 



rounded or subquadrate venter ; umbilicus less than one third total 

 diameter, funnelform; ribs begin with distinct umbilical tubercle, 

 divide almost at once, gently sigmoid, and become more prominent 

 and wider near outer margin where they bend distinctly forward. 

 Upper Horsetown of California, common. 



ACANTHOCERATIDA. 



CXLIX. Lyticoceras Hyatt. 

 Like Hoplites but the nodes weak or absent, venter flat without 

 furrow, the ribs more or less fading; lateral lappets well developed. 

 Comanchic. 



337. L. hyatti (Stanton). (Fig. 1452.) Comanchic. 

 Sides flat; umbilicus large; ribs somewhat flexuous, mostly 



bifurcating, sometimes simple, continued faintly across the venter 

 which is flat, except in last senile portion of whorl where ribs also 

 become obsolete. 



Knoxville of Oregon. 



338. L. angulatus (Stanton). (Fig. 1453.) Comanchic. 

 Small; umbilical angle abrupt; sides flat; venter flat or slightly 



depressed ; ribs scarcely crossing venter, often somewhat nodose 

 at ventral margin. 



Knoxville of California. 

 13 



