FAMILY LEPAD.E — ANATIFA. 255 



Anatifa vitrea. 



PLATE XXXIV. FIG. 316. 



Anatifa vitrea. Lam. An. sans vert. Vol. 2, p. 500. 



A. id. Wheat-ley, Catalogue of Shells of the United States, p. 4. 



Description. Shell exceedingly thin and fragile, translucent, papyraceous, short triangular ; 

 the dorsal valve forming a distinct angle behind, dilated and enlarged towards the base. Sur- 

 face of the valves with faint incremental lines. Peduncle short. 



Height, 0' 8. Width of base, • 5. 



This was one of the largest of several hundred specimens attached to each other, and to a 

 mass of seaweed floating near the Quarantine ground in the harbor of New-York, in the 

 month of July. It was observed by Mr. Charles Wheatley. The smallest did not exceed 

 0-3 in height. 



Anatifa dentata. 



plate xxxiv. fig. 317. 



(state collection.; 



Anatifa dentata. Beuq. No. 3. Lam. An. sans vert. Vol. 2, p. 500. 



A. id. Dillwyn, Cat. 32, Gould, Invertebrate of Mass. p. 21, fig. 11. 



Description. Shell with the valves more robust than the preceding ; the lateral valves with 

 an elevated ridge from the base to the summit, over which are angulated parallel striae. Apex 

 obliquely truncated. Dorsal valve sharp, compressed, with ten to twelve distinct serrated 

 dentations. 



Color, opake white. 



Height, 1-1. Width of base, 0*4. 



This species I have obtained from the bottoms of vessels in the harbor of New- York. 



Anatifa ljevis. 



Anatifa lavis. BbDO. Ency. Math. p. 166, fig. 1. 



Lcpas anatifera. LlN. Syst. Nat. p. 1109. 



Anatifa lavis. Gould, Invertebrate of Mass. p. 19; woodcut, p. 11. 



Description. Shell with the lower valves triangular, rather obtuse at the summit, slightly 

 wrinkled by the lines of growth, crossed by very faint radiating lines : upper valves triangu- 

 lar, narrow, pointing downward ; tip blunted, and leaving quite a large space occupied only 

 by a membrane. Very near the apex is a distinct angle at the back : apex rounded ; back 

 valve rather broad, not much compressed, sometimes grooved lengthwise. 





