CONCHACEA. MOLLUSCA. VENUS. 87 



State Coll., No. 195. Soc. Cab., No. 1877. 



\'enus notata, Say ; Journ. Jlcad. J\"at. Sc, vi., 271. 



Shell very similar to the preceding, and perhaps merely a local 

 variety. The differences which I shall mention appear, however, 

 to be constant. The shell is less heavy and coarse. The hinge- 

 slope declines less rapidly, so that the posterior side is broader, 

 and its extremity broadly truncated ; the area about the ligament 

 is much more smooth, and usually colored brown or purplish. 

 The concentric ridges are more regular in their distances, are 

 somewhat undulated, and frequently are lost in each other ; on 

 the centre of the shell the ridges seem to have been worn off, 

 leaving the surface nearly smooth ; there are no conspicuous ra- 

 diating lines upon the beaks forming a lattice-work with the con- 

 centric ridges ; but between the ridges are fine Hues of growth. 

 The surface is shining, not chalky, of a flesh-color, and Vv'ith zig- 

 zag blotches of fawn-color or brown ; these, however, are not al- 

 ways present. The interior is wholly of a yellowish-white. The 

 lower outline of the figure shows its form compared with V. mer- 

 cenaria. 



Mr. Say's V. prceparca seems to me to be the same thing, in 

 which merely the zigzag lines are wanting. Lives along the 

 shores of Cape Cod. 



Venus fluctuo'sa. 

 Shell transversely-ovate, lenticular^ wliite^ with a yellowish epi- 

 dermis ; surface with recurved, concentric leaves vanishing at the 

 sides ; areola none. 



Figure 50. 



State Coll., No. 193. Soc. Cab., No. 2333. 



Shell oblong-ovate, lenticular, rather thin, nearly equilateral ; 

 white, beneath a glossy, thin, straw-colored epidermis ; anterior 

 side shortest and broadest ; both ends widely rounded ; beaks slight- 

 ly elevated, with a smooth, heart-shaped space before them, not 

 distinctly defined by any boundary ; surface with from twenty to 

 tw^enty-five concentric waves, not quite extending to the margin, es- 

 pecially anteriorly, so that the marginal edges are plain ; when close- 

 ly examined, these waves or ridges are found to be compressed, 

 thin, and inclined towards the beaks; cardinal teeth three in each 



