TRANSACTIONS OF WAGNER 



TERTIARY FAUNA OF FLORIDA 



and no escutcheon ; surface feebly concentrically striate or smooth, with a 

 polished periostracum ; inner margins not crenate ; pallial sinus angular, well 

 defined ; hinge with three delicate cardinal teeth in each valve, with no lateral 

 teeth ; dorsal margins outside the hinge-plate, faintly grooved. 



Type Psephis Lordi Carpenter, Vancouver. 



The animal has the mantle edges fused below and the siphons are repre- 

 sented by orifices with slightly produced margins without papillae. Anteriorly 

 the mantle is open for the passage of the foot, which is not byssiferous. It is 

 viviparous. The genus is west American, so far as known, and is represented 

 in the Pacific Pliocene. 



Venus rhysomia Gabb was identified by Carpenter with a shell which he 

 called Psephis (V. tantilla Gould), but this is not a Psephidia, and, though not 

 typical, should probably be referred to Transennella. It occurs fossil in the 

 Pleistocene of Santa Barbara, California. 



FAMILY CYRENELLID.E. 



This is the Cyrenellidce of Gray in 1857 and the Cyrenoidida of H. and A. 

 Adams of slightly later date. It contains, as far as known, only one genus, 

 Cyrenoida, common to the brackish waters of the shores of the middle Atlantic. 

 The soft anatomy recalls the Diplodontida ; the hinge-structure is, however, 

 distinct from that of any other Lucinoid. It has an archaic appearance and is 

 composed of, in the right valve, two, and, in the left valve, one intercalary long 

 anterior /-shaped teeth, each representing a potential lateral and cardinal which 

 never reach the point of differentiation. There are no indications of any pos- 

 terior teeth at all. The account of the teeth given in Fischer's Manual seems 

 to have .been based upon one of the fluvial Diplodontida elsewhere recorded 

 under the name of Joannisiella, which were long confounded with Cyrenoida, 

 but which have a perfectly distinct type of dentition. At any rate, for the typi- 

 cal Cyrenoida his description is inaccurate both as regards the number and 

 form of the teeth. 



The animal has a foot resembling Loripes, gills and palpi like those of 

 Diplodonta, and united rather elongate siphons, but, curiously enough, no sinus 

 in the pallial line. 



Genus OYBENOIDA Joannis. 

 Cyrenoida Joannis, in Guerin, Mag. de Zool., 1835 (June), pi. Ixiv. and text. Sole example 



C. Dupontia Joannis, loc. cit., Senegal. 

 Cyrenclla Deshayes, in Guerin, Mag. de Zool., 1836 (Feb.), pi. Ixx. and text; Chenu, Man. 



de Conch., ii., p. 105, 1862; Fischer, Man., p. 1096, 1887. 



