CLASS V 



CEPHALOPODA 



645 



tremities or dorsal sutures produced and corresponding with the inner parts of the 

 external sutures. 



MeeJcoceras Hjatt (Fig. 1228); Nicomedit es Toula (Koninckites) ; Clypeoceras i\om. 

 nov. (Aspidites Waagen), of which the type is Aspidites 

 superb as Waagen ^ ; Proptychites Waagen. Triassic. 



Family 16. Gymnitidae Waagen. 



Smooth, compressed, discoidal shells loith rounded 

 venter in pirimitive forms, becoming involute with acute 

 renter in specialised species. Septa not reaching above 

 the ceratitic stage of development in most genera, but not 

 remaining in the goniatitic stage in any hnoivn genera. 

 Sutures in specialised groups similar in convexity and 

 general aspect to those of the Pinacoceratidae, but 

 having peculiar, highly inclined auxiliaries which are 

 developed apparently from marginals on the umbilical 

 sides of the saddles; no corresponding adventitious 

 inflections. Siphonal saddle similar to that of Meeko- 

 ceratidae, and arms of the ventral lobe narrow. First 

 lateral saddles are dependent on, or attached to the 

 large siphonal saddles, and, often simulate adventitious 

 saddles. 



Gymnites Mois. (Fig. 1229); Buddhaites Diener ; 

 Anagymnites Hyatt. Type A. (Gymnites) lamarcki (Diener). 

 Type P. (Plac.) sakuntala (Mojs.). Trias. 



Xenodiscus and Xenaspis Waagen. Permian and Trias. Ophiceras Griesbach (Fig 

 1230). Trias. Flemingites ^Yaagen {Fig. 1231). 

 Trias. Japonites Mojs. Trias. Europe and Asia. 



The Gymnitidae are commonly regarded as a 

 subfamily under the Ptychitidae, but they are 



X 



Fig. 1228. 



Mcckoceras inushhaclMnum White. 

 Lower Trias ; Idaho. x 1/2 (after 

 Hyatt and Smith). 



Paragymnites Hyatt. 



PIT 



Fig. 1229. 



Gymnites pahnal Mojs. Muschelkalk ; 

 Schreyer Alp, near Gosau, Austria. 



Fic. 123U. 



Ophiceras jacksoni H. and S. Lower Trias ; 

 Idaho (after Hyatt and Smith). 



more probably an offshoot from the Lecanitinae, and through them from the 

 Gephyroceratidae. 

 1 The uaiue Aspidites was preoccupie<l when Waagen u.sed it, and a new one becomes necessary. 



