884 Report oF THE STATE GEOLOGIST. 
Subgenus Antiptychina, Zittel. 1883. 
Shells elongate, brachial valve with broad median sinus, having 
elevated margins and a stout plication at its base. Dental plates 
and median dorsal septum well developed. Loop long and fim- 
briate. 
AZ 
Fias. 573-575. Antiptychina inversa, Quenstedt (sp.). (QUBNSTEDT.) 
(Type, Antiptychina bivallata, Deslongchamps (sp.). Jurassic — 
Cretaceous.) 
Subgenus Microthyris, Deslongchamps. 1884. 
Synonym; Ornithella, Deslongchamps, 1884. 
Elongate-oval shells with smooth surface, abrupt anterior 
slopes, dental plates and long loop. 
Fias, 576-578. Microthyris_lagenalis, Schlotheim (sp.). (DAvripson.) 
(Type, Microthyris lagenalis, Schlotheim (sp.). Jurassic.) 
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