1906.] MOLLUSKS FROM THE PERSIAN GULF. 795 



anticum. leniter roiundato ; costis radiantibus permmnerosis, 

 ad 48, nitidis, fere kevibus, cdbis, interstitiis sub lente obscure 

 squcmiatis ; pagina interna alba, margine undique profunde 

 sidcato ; dentibus ad 44, interdtmi bifurcatis ; area ligamentari 

 angusta. 

 Alt. 27, lat. 34, diam. 25 mm. 



Hab. Persian Gulf, Thairi (1903). 



One specimen only, but in superb condition. The many uniform, 

 close-set ribs, and peculiar flattened compression in the umbonal 

 i-egion, chai-acterise this new form, which I would venture to 

 dedicate to my friend Miss Caroline Birley, who has from the first 

 been very interested in all that appertained to the elucidation of 

 the Mollusca of the Persian Gulf, both recent and fossil forms. 



Arca (Scapharca) cibotina* Melvill, sp.n. (Plate LIY. fig. 4.^ 



A. testa iucequilaterali, cequivalvi, transversa, antice angusta, 

 postice expansa, alba, tenui, superficie undique delicate et arete 

 radiatim lirata et cancellata; margine dorsali recto, ventrali 

 plies mimts sinuato ; u.7nbonibus prooni/nidis, contiguis, dentibus 

 anticis 5 vel Q, jwsticis ad 15; pagina interna subhyalina, 

 albo-lactea, delicata. 



Alt. 5, lat. 8, diam. 2 mm. 



Hab. Persian Gulf : Gulf of Oman. Lat. 24° 58' N., long. 56° 

 54' E. ; 156 fathoms, shell-sand. Fairly abundant, but all dead 

 shells. 



This small member of the Arcacea seems distinct. We ally with 

 it A. cidebrensis Smith, from Oulebra Island, W. Indies t- All 

 our examples are of much the same dimensions, and probably 

 nearly or quite adult. 



Arca (Scapharca) clathrata Reeve. 



P.G. Gulf of Oman. Lat. 24° 58' K, long. 56° 54' E. ; 156 

 fathoms, shell-sand. 



Small imperfect specimens referred here with a little doubt. 

 They may prove to be the allied A. consociata Smith (Rep. 

 ' Challenger ' Exp. xiii. p. 266, pi. xvii. figs. 7-7«), which they much 

 resemble in size and general character. 



Arca (Scapharca) injequivalvis Brug. 



P.G. Yoimg examples, most probably referable to this 

 species, have been dredged off Maskat at 15 fathoms. 



I. Bombay ; common and fine {Abercrombie). Bombay to 

 Panjim and Goa [Lt.-Col. H. D. Olivier). 



Arca (Scapharca) japonica Reeve. 

 I. Bombay (^Abercrombie). 



* K-ijSoiros, a chest or coffer. 



f Report ' Challenger ' Exped., Zoology, vol. xiii. p. 268, pi. xxii. figs. 9-95. 



