CLASS V 



CEPHALOPODA 



031 



complex digitate, but always with few lobes and saddles; auxiliary series, if present, 

 short ; adventitious series consisting of not more than one lobe. 



Fio. liiOl. 



Septa of ThalasDocerrtf! 

 'phillipsi Gemmel. Permian ; 

 Sicily (after Geininellaro). 



Fio. 1200.^ 



Dimorphoceras texanum Smith. Coal 

 Measures ; Texas, x i/i (after J. P. Smith). 



Fio. 1202. 



Septa of Ussuria waacjeni Hyatt and Smith. 

 Lower Trias ; Idaho. 



This family is jirobably derived from Aganides of the Devonian and Lower 

 Carboniferous. There is a 

 general resemblance to the 

 development of the Carni- 

 tinae, in the formation of 

 adventitious lobes, but 

 there is probably no kinship 

 with that group. 



Dimorphoceras Hyatt 

 (Fig. 1200). Carboniferous. 

 Thalassoceras Gemm. (Fig. 

 1201). Permian. Ussuria 

 Diener (Fig. 1202). Lower 

 Trias. Sturia Mojs. Alpine 

 Trias. 



Family 11. Ptychitidae 



Mojsisovics. 



Similar in aspect to 

 the more robust forms of 

 Meekoceratidae, but having 

 subacute venters, more com- Fio. 1203. 



plex sutures, and the auxil- Pty'Mtes flexuosusUojti. ( = Amviuiiites stndeH'H.a.wr ■{).p.). Muschelkalk; 

 . • , • 7 J Schreyer Alp, Salzburg, Austria. 



lary series stratghter. 



Ptychites (Fig. 1203), Japonites and Nannites Mojs.; Parannites Hyatt and Smitli. 

 Owenites Hyatt and Smitli. Trias. 



