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TERTIARY FAUNA OF FLORIDA 



33-35, 1848) ; = C. aliforinis Conrad, Am. Journ. Conch., ii., p. 76, 1866; Shell 

 Bluff group, Vicksburg, Mississippi; + C. (Tiza) ainara de Greg., Mon. 

 Claib., p. 234, pi. 37, figs. 12-14. 



Section Aiihvthyris Conrad. 



Like Corbnla, but larger, with heavy, smooth shells, the beaks strongly 

 prosogyrate, thus twisting the plane of the ligament out of the vertical into 

 an oblique or nearly horizontal direction ; form very variable; inhabiting fresh 

 or brackish water. Type A. oblitjita Gabb. Fresh-water Tertiaries of the 

 Amazon. 



Section Anticorbitla Dall. 



Shell thin, the left valve larger, the hinge reversed ; the ligament exter- 

 nal ; resiliuni as in Anisolhyris. Type A. (Himella) fluviatilis H. Adams. 

 (Hiinella Ads., 1860, not Dallas, 1854.) Recent, Amazon River. 



Section Anisor/iviif/itis Conrad. 



Valves subequal, smooth or concentrically undulated, the shell rounded 

 and inflated in front, prolonged into a long rostrum behind, with an escutch- 

 eon-like area defined by two dorsal keels behind the beaks; hinge and other 

 characters like Corlmla. Type Corbnla pyrifontiis Meek. Brackish-water 

 Tertiaries of Montana. 



Section I'.riniona Daudin. 



Shell elongate triangular, feebly concentrically sculptured with a con- 

 spicuous epidermis, the left timbo superior, though the left valve is not the 

 larger; hinge of a strong, nearly vertical process supporting the resilium, 

 with a small socket on each side in the left valve; in the right valve a deep 

 central pit for the resilium, the edges of the hinge-plate bordering it turned up 

 on each side as a narrow projection fitting into the sockets opposite, but no 

 well-defined cardinal tooth or laterals ; the ligament is obsolete. Type ]\Iya 

 lalriata Maton, from Brazilian estuaries. l\>tanioinya Sby., 1835, and Azara 

 Orbigny, 1839, arc synonymes. 



Section Hot/inx-nrlnifa Gabb. 



Shell ovate, solid, pointed behind; valves similarly sculptured with strong 

 concentric ridges; lunular region impressed, sometimes forming a globular 

 cavity in the hinge-margin; shell otherwise like Cuncocorbiila. Type Corbnla 

 ia (iuppy. Oligoccne to recent in the Antillean region. 



