AET. 17 MOLLUSKS FROM WYOMING EEESIDE AND WEYMOUTH 13 



truncated. Poorly defined and irregular ribs show between the 

 tubercles. Ventral part of shell unknown. Suture unknown. 



This species is characterized by its small umbilicus and strong um- 

 bilical tubercles and differs in these characters from Kanabiceras 

 kamxibense. A specimen in hand from the Mowry shale of central 

 Wyoming is very much like K. wyomingense and may be identical, 

 though it is not as well preserved. The writers know of no other 

 species which could well be brought into comparison here. 



Holotype.—C2.t. No. 73773, U.S.N.M. 



Family ENGONOCERATIDAE Hyatt 



Eight specimens of an engonoceratid ammonite are contained in 

 the collection. The family Engonoceratidae Hyatt has been variously 

 interpreted but is probably best viewed as containing the genera 

 Protengonoceras Hyatt, 1903, Engonoceras Neumayr and Uhlig, 1881, 

 Hypengonoceras Spath, 1922, Parengonoceras Spath, 1924, Meten- 

 gonoceras Hyatt, 1903, and Epengonoceras Spath, 1924. At one time 

 or another there have also been included, probably because of the 

 possession of relatively simple, rounded saddles, Neolohites Fischer, 

 Hoplitoides Von Koenen, Indocea-as Noetling, Sphenodiscus Meek, 

 and Flichia Pervinquiere, but they would seem better placed in other 

 families. 

 As thus constituted the family may be characterized as follows : 

 Shell much compressed, discoid, narrowly umbilicate. Venter 

 truncated, though very narrow in several genera, becoming rounded 

 in old age. Flanks smooth or with broad low falcate folds. Septa 

 gently curved, not deeply incised, containing in the adult many lobes 

 and saddles; lobes only moderately serrated, saddles often rounded, 

 entire; ventral lobes short, simple, spreading, usually with pointed 

 short, entire siphonal saddle. 



The constituent genera may be briefly characterized as follows : 

 Protengonoceras Hyatt,^'' genotype P. gdbhi (Bohm). Albian- 

 ?Turonian. Shell smooth except in late stages where folds appear. 

 Venter concave, bordered by sharp, smooth ridges. Saddles usually 

 very broad and short, lobes with few marginals. 



Engonoceras Neumayr and Uhlig,-^ genotype E. jnerdenale (Von 

 Buch). Albian-?Cenomanian. Three distinct lines of nodes. Ven- 

 ter flat with nodose edges in earlier stages; broad, often with zigzag 

 outline in later stages. Saddles deeper than in Protengonoceras and 



" Hyatt, Alpheus, Pseudoceratites of the Cretaceous : U. S. Geol. Survey Mon. 44, p. 153, 

 1903. 



^ Neumayr, Melchior, and Uhlig, Victor, Cephalopoden der Hilsbildungen Norddeutsch- 

 lands: Paleontographica, vol. 27, p. 12, 1881. 



Bohm, Johannes, Uber Avimonitcs pcdernalis Von Buch : Zeitschr. Deutsch. gcol. Gcsell., 

 vol. 50, pp. 183-201, pis. 5-6, 1898. 



