CLASS V 



CEPHALOPODA 



669 



Subfamily C. Acanthoceratinae Hyatt. 



Robust and nioderately evolute forma. Surface highly ornamented witli ribs 

 either simple or bifurcating. Rows of tubercles usiially present on ribs, and often a 



Fi(i. 1303. 

 Acanthoceras rhototnagense (Defr.). Cenomanian ; Rouen, France (after Quenstedt). 



Fio. 1304. 

 Douvilleweras mamiUarc (Schloth.). Gault ; Macherom^nil, Ardennes. 



median row, sometimes uniting in a keel. Septa deeply digitale, the first lateral 

 saddle being bifid. 



Acanthoceras Neiimayr (Fig. 1303); Douvüleiceras Gross. (Fig. 1304); ITiur- 

 mannia Hyatt ; Steueroceras Cossmann {Odontoceras Steuer) ; Mammites Laube and 

 Bruder : Muniericeras and Barroisiceras Gross. Cretaceous. 



Subfamily D. Crioceratinae Hyatt. 



A heterogeneous group of degenerate forms, probably derived from several different 

 normal groups. Forms higbly ornamented witli. ribs and spines or knota. The 



