CLASS V 



CEPHALOPODA 



669 



Subfamily C. Acanthoceratinae Hyatt. 



Robust and moderately evolute forms. Surface highly ornamented with ribs 

 either simple or bifui'cating. Rows of tubercles usually present on ribs, and often a 



Fii:. 1303. 

 Acanthoccrcif rhotoiAaijerise (Del'r.). Cenoinanian ; Rouen, France (after QiieiLstedt). 



Fia. 1304. 

 Douvilleiceras mamillare {Schloth..). Gault; Macheromenil, Ardenne.s. 



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

 saddle being bifid. 



Acantlwceras Neumayr (Fig. 1303); Douvilleiceras Gj'oss. (Fig. 1304); TJiur- 

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

 Bruder : Muniericeras and Barroisiceras Gross. Cretaceous. 



Subfamily D. Crioceratinae Hyatt. 



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

 normal groups. Forms highly ornamented with ribs and spines or knots. The 



