CLASS V 



CEPHALOPODA 



651 



The family of the Phylloceratidae is the most persistent and the longest-lived 

 among the Ammonoids, being continuous from the Permian to the Upper Cretaceous. 



Subfamily A. Monophyllitinae Smith. 



Shells compressed, discoidal, evolute. Septa with primitive monopliyllic saddles, 

 and more regular in the relative size of the lobes and saddles than the succeeding 

 group. Antisiphonal lobe bifid, but otherwise entire. Monoi)hyllites Mojs. (Figs 

 1245, 1246) (Mojsvarifes Pompeckj); DiscophijUifes Hyatt (type Lytoceras patens Mojs.). 

 Triassic. Discophyllitcs forms a connecting link with the Phylloceratinae, and might 

 with equal propriety have been classed with that group. 



Subfamily B. Phylloceratinae Zittel. 

 Form usually involute. Septa very complex, with the saddles deeply digitate, 



Rharoi^lryllites ncojuniisis {Ql\iiii\sie.At). Keuper ; Hallstadt, Austria. 



Fig. 1248. 



PhyUoceras heterophyllum (Sowb.). Upper 

 Lias ; Whitby, Yorkshire. 



Fio. 1249. 



PhyUoceras ptychoicum (Quenstedt). Tlthonian ; Stramberg, 

 Moravia. AL, Antisiphonal lobe. 



