234 NEW- YORK FAUNA MOLLUSCA. 



FAMILY ANATINIDJE. 



Shell transverse, inequivalve, inequilateral , fragile, somewhat pearly, slightly gaping at 

 one end. Hinge with a thickening or spoon-shaped process, to which the ligament is 

 attached, usually supported within by an ossiculum. 



Obs. This family is formed from a part of the family Myaires of Lamarck, and is intended 

 to correspond with the Osteodesmaces of Deshayes, as it has been revised and extended by 

 Mr. Couthouy. 



GENUS OSTEODESMA. Deshayes. 



Shell oblong, transverse, trigonal, thin, fragile, pearly, inequivalve, slightly gaping at its 

 ends. Hinge linear, having on each valve a narrow ledge to which the ligament is attached, 

 and against which adheres, by its upper surface, a four-sided ossiculum. Muscular im- 

 pressions small, the anterior elongated, the posterior rounded. Palleal impression with 

 an excavation behind. 



OSTEODESMA HYALINA. 



PLATE XXXIII. FIG. 311. i. B 



(STATE COLLECTION.) 



Mya hyahna. Conkad, Joum. Acad. Nat. Sc. Vol. 6, p. 261. pi. 11, fig. 12- 

 Lyonsia id. Id. Amer. Mar. Conch, p. 51, p], 11, fig. 2. 

 Amphidesma corbuloides. Mass. Cat. p. 25, 



Osleodcsma hyalma. CouTHOuy, Bost. Joum. Nat. Hist. Vol. 2, p. 160. 



O. id. GoULD, Inyertebrata of Mass. p. 46, fig. 31. 



Description. Shell thin, fragile, pellucid, transversely elongated ; anterior side short and 

 rounded ; posterior side longest, produced, narrowed, compressed, slightly truncated and re- 

 flected at the end. Beaks prominent, inclined forwards, polished within. Surface with a 

 thin membranaceous epidermis, which is concentrically wrinkled and corrugated by radiations 

 most evident on the posterior portions. Umbones smooth and polished. Hinge with a deli- 

 cate edge extending from the beak obliquely downward and backward, serving for the attach- 

 ment of a ligament, which is also attached to the edge of the wedge-shaped ossiculum -lying 

 against that part. Color, pearly white. 



Vertical axis, 0"35 ; transverse ditto, 0'6. 



This exceedingly delicate little shell occurs along the sandy beaches of Long island. It 

 has also been dredged from deep water at the Quarantine ground. 



