I40 NORTH AMERICAN INDEX FOSSILS. 



with angular shoulders of all whorls exposed ; septa close ; generally 

 three to four wide shallow constrictions on internal mold. 



Goniatite limestone (Kinderhook) of Indiana, and Marshall 

 group of Michigan. 



208. M. parallelum (Hall). (Fig. 1392, /-/t.) Mississippic. 

 More compressed laterally than preceding; whorls higher, um- 

 bilicus smaller, septa closer. 



Kinderhook of Indiana (Rockford Goniatite bed), and Michigan 

 (Marshall group). 



LXXXIL GoNiOLOBOCERAs Hyatt. 



In general form like the preceding, but with extremely angular 

 lobes ; sides flattened. Mississippic-Carbonic. 



209. G. goniolobus Meek. Carbonic. 

 Of moderate size ; sides gently convex ; umbihcus small ; lobes 



and superior lateral saddle deep and sharply angular or pointed; 

 ventral saddle with small angular notch. (Type of genus.) 

 Coal Measures( ?) of New Mexico. 



210. G. welleri Smith. (Fig. 1392, a-c.) Carbonic. 

 Smaller than preceding, with flatter sides, more compressed lat- 

 erally and with narrow venter, angular and slightly furrowed; 

 ventral saddle with tongue-shaped extension instead of notch. 



Coal Measures of Illinois and Texas. 



LXXXIII. DiMORPHOCERAS Hyatt. 



Compressed, smooth, involute goniatites, with narrow umbilicus ; 

 surface with curved growth lines only; suture has ventral lobe 

 divided by a deep, notched, siphonal saddle, with additional narrow 

 saddle in the lobes thus formed, making a pair of narrow, ventral 

 lobes on each side of the abdomen; a deep, pointed, lateral lobe 

 in middle and another on umbilical shoulder; anti-siphonal lobe 

 tongue-shaped, flanked by pointed laterals. Carbonic. 



211. D. texanum Smith. (Fig. 1393, />-r.) Carbonic. 

 Greatest breadth at umbilical shoulder ; venter narrow, flattened, 



angular and slightly furrowed at maturity, rounded in youth. 

 Upper Coal Measures (Cisco) of Texas. 



