234 NEW-YORK FAUNA — MOLLUSCA. 
FAMILY ANATINID:. 
SHELL transverse, inequivalve, inequilateral, fragile, somewhat pearly, slightly gaping at 
one end. Hinge with a thickening or spoon-shaped process, to which the ligament 1s 
attached, usually supported within by an ossiculum. 
Oss. This family is formed from a part of the family Myaires of Lamarck, and is intended 
to correspond with the Osteodesmacés 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. a. b. 
(STATE COLLECTION.) 
Mya hyalina. Conrap, Journ. Acad. Nat. Se. Vol. 6, p. 261. pl. 11, fig. 12. 
Lyonsia id. Yp. Amer. Mar. Conch. p, 51, pl. 11, fig. 2. 
Amphidesma corbuloides. Mass. Cat. p. 25, 
Osteodesma hyalina. Coutnouy, Bost, Journ. Nat. Hist. Vol. 2, p. 166. 
oO. id. Goutp, Invertebrata 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. 
