858 Rerort or tar Stare Groxogist. 
Type, Votothyris subvescicularis, Davidson (sp.). 
Distribution. Devonian? — Carboniferous. 
: aye” 
Fia, 474, Fia. 475. 
Notothyris subvescicularis, Davidson. 
Fia. 474, A dorsal view of the exterior. ~« 
Fia. 475. A profile of the same shell. 
Fia. 476. The interior of the brachial valve; showing the perforated hinge-plate and the 
lateral lamelle of the loop. (WAAGEN.) 
Juvavella, Bittner. 1890. 
Shells smooth, biconvex, with a low median sinus on the pedicle- 
valve. Brachial valve with a very short loop, the descending 
branches uniting to form an expanded vertica] median plate. 
Fics. 477, 478. Juvavella Suessi, Bittner. (BITTNER.) 
Type, Juvavella Suessi, Bittner. 
Distribution. Trias. 
Nucleatula, Bittner. 1890. 
Shells having the general external aspect of those of JuvavgLLa 
but with a larger loop in which the vertical median plate is 
highly developed and fimbriated on its anterior margins. 
Fies. 479-484. Nucleatula retrocita, Suess (sp.) (BITTNER. 
Type, Vucleatula retrocita, Suess (sp.). 
Distribution. Trias. 
110 
