CEPHALOPODA— AMMONOIDEA. 



197 



venter, the margins of which are tuberculated. Sutures with a 

 rather ragged appearance, the first lateral saddle bifid, the first 

 lobe deeper and larger than the others. Young coronate, with 

 large lateral tubercles. Cretacic. 



342. M. swallovi (Shumard). (Fig. 1457, a, &.) Cretacic. 



Umbilicus moderate; ribs frequently bifurcating near umbilicus; 



rir: 



ih^Tvm^ 



Fig. 1457. a, b, Metoicoceras swallovi, X /^j ^^^ suture ; c-e, M. wki/ei, two views 

 and suture, X )^- (After Hyatt.) 



ventral concavity frequently smooth, bordered by rounded nodes; 

 suture rather simple, the first lateral saddle divided by shallow 

 notch, with three notches on the outer and one on the inner (ven- 

 tral) margin. 



Coloradoan of Texas and Utah. 



343. M. whitei Hyatt. (Fig. 1457, c-^.) 



Larger, more compressed, umbilicus smaller, sides flatter, nodes 

 less pronounced, more nearly a part of the ribs; secondary ribs 

 extending only about half way to umbilicus; suture more complex, 

 with deeper and more numerous incisions. 



Coloradoan of Texas and Kanab Valley, Utah. 



