CEPHALOPODA— AMMONOIDEA. 



Glyphioceratida. 



LXXXIV. GoNiATiTES de Haan. 



Involute, globose shells with minute or closed umbilicus ; sutures 



with mostly sharp lobes and saddles, a narrow, notched, siphonal 



saddle, and a narrower, siphonal lobe. Mississippic. 



212. G. crenistria Phillips. (Fig. 1393, /-/z.) Mississippic. 



Fig. 1393. a-c^ GaslriocerassubcavumyS\it\\y(^%, diVid snixxro.; d, e, Schistoceras 

 hildrethi, X Yi '■> f-^i Goniatites crenistria^ shell X Yzi ^"^ suture ; i-l, G. striatus^ 

 shell X Yzi ^^^ suture internal and external ; ni-o, G. subcircularis, shell % ; <?, suture 

 enlarged ; p-r, Dimorphoceras texanum, suture and shell X %• (^'^ after J. P. 

 Smith.) 



Whorls semilunar in section ; umbilicus very narrow ; four or 

 five constrictions to a volution; surface with distinct cross striae, 

 with fine, sharp crenulations, which show only towards maturity; 

 incipient nodes formed by bundling of striae at umbiHcus. 



St. Louis-Chester of Texas (Bend), and Arkansas (Spring 

 Creek and Fayetteville) ; also common in Europe. 



