MIOCENE MOLLUSCA AND CRUSTACEA. 71 



Genus ARTENA Conrad. 

 Am. Jour. Conch., vol. 6, 1870, p. 76. 



" Triaiifjiilar, thick ; surface with acute, concentric, prominent ribs; hinge 

 with three cardinal teeth in the right valve, two of them diverging, distant, 

 the anterior one under the apex, robust, direct, curved; left valve with three 

 diverging distant teeth; lateral tooth very small, pyramidal; pallial sinus 

 very small and angular. 



"Cijtherea staminea Com-ad, Miocene Foss., PL xxi, fig. 1. 



"This genus is readily distinguished from the other genera of the 

 family by one thick anterior tooth in the right valve instead of two approx- 

 imate teeth as in Meretrix, Caryatis, etc., and by two distant, thick, neai'ly 

 equal teeth of the opposite valve, and also by the very small pallial sinus, 

 the exterior ribs, etc." 



The above is Conrad's description of this genus given iu the Am. Jour. 

 Conch., 1871, being copied literally by Tryon in his Systematic and Struc- 

 tm-al Conchology, where he gives the orthography of the name Ai-tenia 

 and dates it 1870. A specimen of A. staminea which is probably from 

 South Carolina, and is fully grown and much thickened, shows the teeth 

 well developed. Those of the right valve are as Mr. Conrad describes 

 them, except perhaps that the one opposite or beneath the beak is not 

 "curved." It is "direct;" but it would be difficult to interpret it as curved 

 in any sense. The anterior tooth in the right valve is small and the pos- 

 terior one large, while in the left valve the reverse is the case. As to the 

 merits of the genus, it appears to me that all the features of it are fully 

 embraced in those of Anaitis of Roemer, as shown in Venus plicaia Gmelin, 

 and that the separation was not necessary. Furthermore, the typical 

 species, A. staminea Conrad, is much more neai'ly allied to Venus tlian to 

 Cytherea, under which it is placed by Tryon. 



