1917.] Natural sciences of Philadelphia. 197 



Venericardia santodomingensis n. sp. 



Cardiia scabricostala Guppy, Gabb, Trans. Amer. Philo.s. Soc, XV, 1873, 

 p. 252. Not of Guppy. 



The shell is rounded-oval, the length very slightly exceeding the 

 altitude, beaks very near the anterior end; lunule moderately sunken 

 and rather large. Sculpture of 22 or 23 subacute ribs bearing small, 

 somewhat transverse granuU^s, the intervals between the ribs broad, 

 concave, irregularly striat(xl transversely. Hinge and basal margin 

 as in V. scabricostala (Guppy). 



Length 21.7, alt. 21.3, semidiameter 9 mm. 



Type No. 3214, A. N. S. P. 



This species is closely related to V. scabricostala, })ut differs by 

 having more ribs, which are narrower with wider intervals; it is 

 rounder, and higher relative to the length. We find these differences 

 constant in large series of both examined. It has some resemblance 

 to the young of V. hadra Dall, but that seems to be a heavier, far more 

 coarsely sculptured shell, when specimens of equal size are com- 

 pared. The Chipolan species reaches a far greater size than V. 

 santodomingensis. 



•Echinooliama trachyderma n. sp. 



Chama arcinella Linn., Gabb, Trans. Amer. Pliilos. Soc, XV, 1873, p. 2.51. 



Shell resembling E. antiquata Dall in shape, but differing by having 

 fewer radial ribs (8 to 12), which are only sparsely spinose; surface 

 very closely and strongly tuberculate, the tubercles sometimes 

 anastomosing into a netted pattern in places. 



Length 55.5, alt. 61.5, diam. 43.5 mm. 



Type No. 2766, A. N. S. P. 



The comparison of long series of excellently preserved shells from 

 Bowden and Santo Domingo shows no intergradation between 

 E. antiquata and this species. 



Phacoides perplexus n. sp. 



Lucina antillarum Reeve, Gabb, Trans. Amer. Philos. Soc, XV, p. 251. 



The shell is small, orbicular, not very inequilateral, with sculpture 

 of numerous (about ten) rounded radial ribs, which gradually dimin- 

 ish and partly disappear on the lower third of the disk, crossed by 

 many close, fine, obtuse and slightly waved concentric threads. 

 Lunule distinct, somewhat sunken. Hinge with two cardinal teeth 

 but no laterals in the left valve. Anterior muscle scar long. Internal 

 margin crenulated. 



Length 7, alt. 6.7, diam. left valve 2.3^ mm. 



With a hinge like Lucinoma, this species has external sculpture 

 14 



