1917.] NATURAL SCIENCES OF PHILADELPHIA. 187 



concentric threads are not quite so well developed. Tooth-row 

 continuous, but an enlarged tooth separates the anterior series of 

 30 teeth from the posterior series of 36; the length of the two being 

 as 3 : 4, or as 2 : 3. Margins are deeply fluted, as usual. 



Length 60, alt. 37, diam. 36.5 mm. 



Type No. 2731, A. N. S. P. 



This shell is related to A . halidonata, but it is much narrower, the 

 ribs are not grooved and not so numerous, the beaks are smaller, 

 the cardinal area has more grooves, etc. In ^4. anliquata L. the 

 beaks are turned forward less, the anterior angle is more produced, 

 and the cardinal area has fewer grooves. Both A. halidonata and 

 A. antiquata have impressed lines or grooves along the posterior 

 ribs, in large examples, which are wanting in A. copiosa. 

 Area (Scapharca) devexa n. sp. 



The shell is somewhat trapezoidal, much inflated, with wide, 

 moderately prominent beaks which are widely separated by a rather 

 wide, fiat cardinal area. Anterior and posterior ends oblique, roughly 

 parallel, the anterior convex, posterior somewhat straightened; basal 

 margin strongly convex. Sculpture of 26 square ribs somewhat nar- 

 rower than their intervals, unevenly granose, the granules transverse, 

 subobsolete in places, and on the posterior ribs weaker on the right 

 valve, some of the anterior ribs are bifid in the left valve. Intervals 

 sharply striated transversely. The cardinal area has many regular 

 grooves over the whole poster'or part, but anteriorly only the central 

 part is grooved, the sides being smooth. The anterior end of the 

 hinge line is strongly angular. Tooth-row continuous. 



Length 42, alt. 30, diam. 31 mm. 



Type No. 2727, A. N. S. P. Valves of 5 other individuals. 



This species has a characteristic form. The close, regular grooves 

 of the cardinal area, which has smooth sides anteriorly, is also 

 notable. 

 Area (Soapharoa) intumulata n. sp. 



The shell is somewhat trapezoidal, inflated, with mesially impressed, 

 beaks slightly before the anterior fourth. Cardinal area rather 

 narrow, with a few grooves, bounded by a narrow ridge. Sculpture, 

 in left valve, of 35 ribs about as wide as their intervals, crossed by 

 concentric threads which are slender in the intervals, widened on 

 the ribs. The right valve is like the left except that the concentric 

 sculpture is slightly weaker. A few of the anterior ribs have a 

 central sulcus. Hinge rather narrow, the tooth-row continuous, 

 of 23 and 29 teeth. 



