76 MAZATLAN BIVALVES 



often purple, especially on the hinge line. The smallest valve 



is "03 across ; the largest measure? long. 1*9, lat. 2*, alt. I' 28. 



Hob. St. Elena, in coarse sand at low water, Cuming. 



Ecuador ; St. Elena, D'OrUgny.$. W. Mexico, P. P. C 



Mazatlan ; extremely common ; L'pool fy Havre Coll. 



Tablet 357 contains 7 young valves, [?], lunule not defined, 

 very faint concentric lines of growth, anterior tooth elongated, 

 as is usual in young Veneridse. 



Tablet 358 contains 7 specimens of the normal chocolate 

 colour. 359, 7 do. with white umbos. 360, 7 do. purplish 

 tinge. 361, 7 do. light coloured, slightly spotted. 362, 7 do. 

 with large patches of dark. 



108. VENUS (? CHIONE) , sp. ind. 



Tablet 363 contains 3 small valves, the smallest only '02 

 across, smooth and white, which do not accord with any of the 

 foregoing species. 

 Hob. Mazatlan ; in shell washings : L'pool Col. 



GENUS TAPES, Megerle. 



This genus, though the type of a sub-family of Gray, (B. M. 

 Cat Ven., p. 159) approaches Venus (Chione, Megerle, Grray,) 

 by insensible gradations. The following species may be ranked 

 with either genus. The typical forms have not yet been found 

 in this Zoological province. 



109. TAPES HISTRIONICA, Brod. fy Sow. 



Venus histrionica Proc. Zool. Soc. 1835, p. 41. Hani. Descr. 



Cat. p. 119 ; Wood. Swppl. pi. 16, f. 31. B. M.^ Cat. D'Orb. 



Moll. p. 67, no. 594 Sow. Thes. Conch, p. 714, pi. 55, f. 52. 

 Chione histrionica, Desk. B. M. Cat. Ven. p. 139, sp. 60. 

 Tapes histrionica, Hani. Col. suo. 



This belongs to a group of very closely allied species, of 

 which T. granulata (B. M. Cat. Ven. p, 138,) is the W. Indian 

 analogue, and T. straminea the Calif ornian. It has the form 

 and sculpture of a Tapes, with the teeth and pallial sinus of a 

 Venus. The form varies in the greater or less development of 

 the posterior angle, and in the flattening or rounding of the 



