402 



MOLLUSCOIDEA 



PHYLUM V 



Subfamily A. Megalanterinae Waagen. 



Paleozoic Terehratulidae with a long loop giving off ascending branches. Shell 

 smooth. Devonian to Carboniferous. 



Fig. .097. 



Stringocephalus hurtlni Defr. Devonian ; Patfratli, near Cologne. A, Side-view, "/g natural size. B, Greatly 

 reduced diagram showing brachidium and median septa. ' ', Young specimen with large delthyriuni and deltidial 

 plates. I), Interior of dorsal vah'e, natural size, partly restored, a, Adductors ; c, Crura ; (', Dental sockets ; 

 I, Loop ; pr, Cardinal process ; x, Median septum. 



Megalanteris (Ehlert {Meganteris Suess). Large, smooth, equally biconvex, 

 sub-oval shells, with the long convergent jugal processes of the loop extending 

 beyond the connecting band of the ascending branches. Devonian ; Europe 

 and North America. 



Cryptonella Hall. Elongate oval shells with short jugal processes. 

 Devonian to Lower Carboniferous ; North America, England and Bohemia. 



Harttina Hall and Clarke. Centronella-\\ke shells with a high dorsal 

 median septum and the descending branches of the loop laterally fringed with 

 irregularly set spinules. Carboniferous ; North America and Brazil. 



(?) CrijptacantUa White and St. John. 

 Upper Carboniferous ; North America. 



Subfamily B. Dielasmatinae, novum. 



Derived Paleozoic Terehratulidae with 

 short loops. Often there are cruralia present. 

 Shells smooth or coarsely plicate. Devonian 

 to Permian. 



Eunella Hall and Clarke. Like Dielasma 

 but without a cruralium. Devonian ; North 

 America. 



Dielasma King (Ejnthyris King, non 

 Phillips) (Fig. 598). Dental lamellae 

 strong. To the divergent crural plates is attached a shalloAV, often quite long, 

 free or sessile cruralium. Devonian to Permian ; Europe, India and America. 



Fig. 598. 

 Dielasma elongatnm(Bch\oth.). Permian; Hum- 

 bleton, England. .1, Dorsal and anterior views, 

 i/i- B, Interior of conjoined valves, greatly en- 

 larged (after Davidson). 



