CEPHALOPODA— AMMONOIDEA. 223 



Mammitida. 



CLXIX. Barroisiceras Grossouvre. 



Involute shells, laterally compressed, ribbed and tubercled, venter 

 with sharp keel broken into tubercles by crov^ding of costse ; some- 

 times in later stages becoming a continuous keel; suture complex, 

 with broad saddles and narrower lobes. Cretacic. 



390. B. dentatocarinatum (Roemer). (Fig. 1502.) Cretacic. 



A row of distant, rounded tubercles surrounds the umbilicus 

 from which the primary costse bifurcate or trifurcate, while addi- 

 tional costse appear between the primary, from three to four in each 

 interspace; each costa with a tubercle near venter; keel broken up 

 into sharp, elongate tubercles by crossing of costse. 



Ripleyan of New Jersey; Austin limestone of Texas; Chico of 

 California {= f Schloenbachia siskiyouensis Anderson). 



CLXX. Schloenbachia Neumayr. 



Involute, more or less widely umbilicated; laterally compressed 

 ammonites, costated and with a comparatively broad venter bear- 



Schloenbachia leonensis, X %• (After Hill.) 



ing a strong median keel; ribs curved sigmoidally, bending more 

 or less strongly forward near venter. Comanchic-Cretacic. 



391. S. (Gauthiericeras) leonensis (Conrad). (Fig. 1503.) 



Comanchic. 



Section of final whorl subquadrangular, umbilicus large, ribs 



strong, marked by two rows of tubercles, one near umbilicus and a 



