172 Bulletin 29 336 



Scapharca losquemadica. n. sp. 

 Plate 30, Figure I 



We collected three left valves of an Area resembling A. in- 

 csquilateralis and A. darie?isis. Ribs about thirty, the anterior 

 sulcated and wider than the interspaces, anterior central ribs 

 high, rounded and very narrow; posterior central ribs larger, 

 higher, rounded, somewhat sulcated; posterior ribs beginning at, 

 or somewhat anterior to, the umbonal ridge, wide, low, flat and 

 square- topped with an incised groove; these posterior ribs are 

 smooth; the rest are nodulose. Hinge line long with an angle at 

 each end; teeth fine and numerous, vertical except at the pos- 

 terior end where they are somewhat inclined; cardinal area nar- 

 row, with a few grooves. Length 37, approximate altitude 20, 

 semidiameter 8 mm. All the full grown shells are imperfect so a 

 young shell has been figured. 



This species should perhaps be classed as a variety of A. in- 

 cequilateralis, but is much larger and the depth is proportionately 

 greater anteriorly. The ribbing is practically the same. Our 

 shell is also akin to A. dariensis Brown and Pilsbry from Gatun; 

 but the description of that species implies that the posterior as 

 well as the anterior ribs are nodulose, and the posterior basal 

 curve is different. 



Locality. — (Exp'd '16) Zone E, Rio Gurabo at Los Que- 

 mados. 



Scapharca caimitaca, n. sp. 

 Plate 30, Figure 13 



This small species belongs to the group of which A, trans- 

 versa in the recent representative. Ribs about thirty, narrow, 

 entire, rising sharply from the nearly equally wide, flat interspaces, 

 ribs triangular in cross section, with the medial line distinctly 

 angulated; both ribs and interspaces are crossed by concentric 

 lines which produce a moderate beading. The right valve is too 

 worn to show if its sculpture is similar to that of the left. Hinge 

 line about two-thirds the length of the shell; teeth small, verti- 



