668 



MOLLUSCA 



PHYLUM VI 



The Cosmoceratidae are probably a polyphyletic group, derived from several 

 branches of the Steplianoceratidae. 



Subfamily A. Cosmoceratinae Hyatt. 



Discoidal and involute forms having at a comparatively early stage or throughout- 



.^ {»ri!*Ti»^ ^^^^ ^^'^ *^^" ^^^'^^ rows of large tubercles 



on each side, and costae interrupted on 

 the venter by a smootli median zone or 

 channel. 



Gosmoceras Waagen (Fig. 1300). 

 Middle Lias to Oxfordian. 



Subfamily B. Hoplitinae Hyatt. 



Discoidal and involute forms with 

 costae bifurcated on the sides at umbilical 



Fi(!. 1300. 



Vosmoceras oniatnm (Sowb.). Callovian (Ornaten- 

 thon) ; Gammelsliausen, Wurteniberg. 



Fii^ 1301. 



HoplUes tuhercujatus (Sowb.). "'■ 



Gault ; Folke.stone, England. HoplUes noricus (iiovih.). { = Hoplites amblygonius 'Neum.). Neocomian ; 

 Siphiincle broken away.j Acliim, near Borsuni, Prussia. 



shoulders ; prominent tubercles at their forks, and also at or near their ventral 

 termini, these last being separated by a median zone or deep channeL Young of 

 some species have costae continuous across the venter, and resemble those of Sonneratia. 

 Parallelism with Cosmoceratinae very close. Sutures resemble those of Mammites, 

 but more comi:)lex. Lateral saddles narrower and more deeply cut, and first lateral 

 saddles often trifid in late stages. Dorsal series with two pairs of complex zygous 

 lobes and saddles on either side of a long, narrow, complex, antisiphonal lobe. 



Hoplites Neum. (Figs. 1301, 1302); Genomanitea Haug {Discoceras Kossmat) ; 

 Sonneratia Bayle ; Neocomites Uhlig. Cretaceous. 



