— 
886 Report or THE StTaTE GEOLOGIST. 
(Type, Aulacothyris resupinata, Sowerby (sp.). Trias — Cre- | 
taceous.) 
Fias. 583-586. Aulacothyris resupinata, Sowerby (sp.). (DavIDSON.) 
Subgenus Epicyrta, Deslongchamps. 1884. 
Smooth naviculoid shells with broad median sinus on pedicle- 
valve and corresponding eievation on the brachial valve. 
Fias, 587, 588. Epic rta Hugenii, von Buch (sp.). (QUENSTEDT.) 
(Type, Epicyrta Eugenii, von Buch (sp.). Jurassic.) 
Subgenus Plesiothyris, Douvillé. 1880. 
Shells biconvex, brachial valve biplicate. Dental plates and 
dorsal median septum present. Loop long. 
(Type, Plesiothyris Verneuilii, Deslongchamps (sp.). J urassic.) 
138 
