882 Report oF THE STATE GEOLOGIST. 
Ceenothyris, Douvillé. 1880. 
Shells elongate-oval, smooth. Dental plates highly developed, 
becoming calloused with age. Hinge-plate large, tripartite 
and supported by a median septum extending one-half the length 
of the shell. Cardinal process absent or very faint. Loop broad 
Fia. 564, Ccenothyris vulgaris, Schlotheim (sp). (KoscHINsKY.) 
and moderately long, theascending branches forming at their union 
a shield-shaped plate which is not attached to the median septum. 
Type, Cenothyris vulgaris, Schlotheim (sp.). 
Distribution. Trias. 
Hynniphoria, Suess. 1858. 
Small, subglobular smooth shells said to contain a “ plowshare”- 
shaped process on the brachial apparatus. Imperfectly known. 
Type, Hynniphoria globularis, Suess. Jurassic. 
Macandrevia, King. 1859. 
Shells biconvex, smooth, elongate-oval. Foramen large and 
without deltidial plates. Pedicle-valve with dental plates. 
a 
Fie. 565. Fia. 566. Fia. 567. 
Fias. 565-567. Macandrevia cranium, Miiller (sp). (DaAvipson.) 
Brachial valve without cardinal process, but with crural plates 
and sometimes the remnant of a median septum. Loop in its 
mature condition similar to that of MaceLianta, 
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