204 new- york fauna — mollusca. 



Anodon benedictensis. 



PLATE XVIII. FIG. 435. 



(STATE COLLECTION.) 



Symphonota benedictensis. Lea, Trans. Am. Phil. Soc. Vol. 5, p. 104, pi. 16, fig. 48. 

 Anodonta id. Adams, Am. Jour. Sciences, Vol. 40, p, 276, 



Description. Shell thin and fragile, trapezoidal, inequilateral, subcompressed : dorsal 

 margin nearly straight. Beaks somewhat prominent, and granulate at tip ; in perfect speci- 

 cimens, with four to five distinct undulations. Cicatrices scarcely perceptible. 



Color. Epidermis light brownish horn, verging to greenish ; the incremental lines some- 

 what darker : within bluish white, slightly iridescent. 



Vertical axis, 1 •5 — 2*3; transverse ditto, 3*0 -4' 2. Diameter, 1*0-1*4. 



From Lake Champlain, and Onondaga lake. In a general revision of this family, it is 

 highly probable that this will be considered as a variety of the preceding. In all the speci- 

 mens which I have seen, one end is covered with a loose earthy coating. It may be observed, 

 too, that they are rather inflated than subcompressed. 



FAMILY CARDIDM. 



Animal as in the preceding. Inhabiting salt water. Shell heart-shaped. Cardinal teeth 

 two or three ; lateral teeth one or two. Epidermis often scanty or wanting ; not iridescent 

 within. 



GENUS CARDITA. Bruguieres. 



Shell equivalve, thick, inequilateral, suborbicular, ribbed. Hinge with a short strong erect 

 tooth under the beaks, and an oblique elongated one along the margin. Epidermis distinct. 



Cardita borealis. 



plate xxii. fig. 247. 

 (state collection.) 



Venericardia cribraria? Say. 



Cardita borealis. Conrad, Am. Mar. Conch, p. 38, pi. 8, fig. 1. 



Ci id. Gould, Invertebrata of Mass. p. 94, fig. 59. 



Description. Shell very thick and robust, suborbicular, heart-shaped. Beaks elevated and 

 recurved : from eighteen to twenty radiating ribs, broader than their distances apart, and 

 strongly crenating the outer margin : ligament nearly concealed ; lunule deeply impressed. 



