406 PROCEEDINGS OF THE ACADEMY OF [PaRT II 



Sowerby, which has also been identified with A. grandis. It agrees 

 better than any other Santo Domingan species with the brief and 

 inconclusive diagnosis of that shell. Sowerby states that his species 

 has "rather more numerous" ribs than A. grandis, and that it "is 

 much more rounded at the inferior margin", "margine inferiori ro~ 

 tundato". As far as it goes, this applies to A. chiriquiensis; yet as 

 no definite information on the type specimen is available, the name 

 given by Gabb is preferred, since there is no doubt about its iden- 

 tity. 



Area chiriquiensis websteri Pilsbry. Plate XLI, fig 4. 



Area websteri Pils., Proc. A. N. S. Phila., 1910, p. 488. 



This form is more leiigthened than A. chiriquiensis and more of 

 the ribs are granose; yet it is probably a form of chiriquiensis. The 

 type valve is figured. 



Length 44, alt. 35, semidiam. 18 mm. 



On a stream between Las Caobas and Hinche, Haiti, W.W. Web- 

 ster. 



Type no. 1312 A. N. S. P. 



Area dolaticosta Pils. and Johns. Plate XLI, flgs. 5, 6. 



Proc. A. N. S. Phila. 1917, p. 188. 

 Chiriqui. 



Area (Scapharca) coccopleura Pils. and Johns. 



Proc. A. N. S. Phila. 1917, p. 188. 

 = A. hispaniolana Maury. 



Area (Argina) tolepia (Dp 11.). 



Scapharca (Argina) tolepia Dall, Tran&. Wagn. Inst., iii, p. 649, pi. 33, figs. 7, 8 



This is one of the most abundant arks. By Gabb the specimens 

 were referred to A . grandis as young. It is somewhat variable. From 

 the adhering material it is evident that several beds are represent- 

 ed. 



Three forms seem to be distinguishable, additional to the typical 

 form. Whether these are species, or successive or synchronous mu- 

 tations of A. tolepia, cannot be determined until their stratigraphic 

 place is known. 



A. arthurpennelli Maury appears to be based upon part of Gabb 's 

 specimens. It may be distinct from tolepia, described from Rio 

 Amina. 



Area tolepia saxea Pils . and Johns. Plate XXXIX, fig. 10, 



Proc. A. N. S. Phila. 1917, p. 189. 



