192 PROCEEDINGS OF THE ACADEMY OF [April, 



anterior, contiguous beaks, the absence or weakness of crenulation 

 along the basal margin, and the concentric waves of the surface of 

 the cast. The shell when found will probably prove to be thin 

 for an Area. Its strong individuality will permit ready recognition 

 of this species, which we know from a single quite perfect cast. 



Glycymeris santodomingensis n. sp. 



Axincea sericata Reeve, Gabb, Trans. Amer. Philos. Soc, XV, 1873, p. 255. 



The orbicular shell is rather convex, solid; anterior end broadly 

 rounded, the posterior end more narrowly so. Sculpture of 22 convex 

 ribs, widest in the middle and anteriorly, much narrower on the 

 posterior third. Hinge broad, with 10 anterior and 13 posterior 

 teeth; median teeth subobsolete; sulci of the lower margin extremely 

 shallow, almost obsolete. Posterior adductor scar bounded by an 

 acute ridge anteriorly. 



Length and alt. 37, semidiameter 11 mm. 



Type No. 2654, A. N. S. P. 



Gabb identified this species with a little knowm recent form, which 

 differs in number of ribs, etc. In G. lloydsmithi P. & B. the ribs are 

 much flatter, the hinge more curved, and the internal margin has 

 strong V-shaped teeth. 



Glycymeris dilfidentiae n. sp. 



Axincea pennacea Lam., Gabb, Trans. Amer. Philos. Soc., XV, 1873, p. 255. 



The shell is slightly inequilateral, rather convex, the posterior end 

 more narrowly rounded and more produced than the anterior. 

 Sculpture of low but distinct radial ribs in the median part, obsolete 

 at the ends; over all are fine radial striae, about six striae (five to seven) 

 between crests of the ribs; these are crossed by regular but extremely 

 minute concentric striae, which pit the grooves between the radial 

 striae, when the surface is unworn. Hinge is little curved, with tooth- 

 row of 14, 15 teeth. The margin has rather strong, short teeth. 



Length 20, alt. 16.7, semidiameter 7 mm. (type). 



" 21, " 18.7, " 7 " (largest valve). 



Type No. 2653, A. N. S. P., with 11 other valves. 



The Bowden G. jamaicensis has a decidedly different sculpture, 

 and fewer much larger teeth in specimens of the same size. The 

 recent G. lineatus (Reeve) has much the same sculpture, but it differs 

 in the teeth and in outline. 



Ostrea bolus n. sp. 



The shell is small, usually subtriangular, the deep valve having 

 the beak strongly curved as in some Gryphaeas, exterior with a few 



