MAZATLAN BIVALVES 161 



Tablet 706 contains a young valve, '68 long, and a larger 

 pair, broad spreading form, hinge straight.— 707, 1 do. hinge 

 spiral. — 708, 3 pairs and a valve, different ages, forms and 

 colours. — 709, Area grandis, with valves of O. Virginica at- 

 tached. — 710, an adult sp. attached to a twig, with another 

 valve, 4'o long, attached to it by its whole length.— Another 

 of inteiTuediate size wiU be found on tablet 20 ; and a valve 

 with Crucibulum. 



Tablet 711 contains a very small Gryph?ea-shaped shell, 

 with spiral umbos, "11 in length, which is probably the young 

 of this species. 



213. OSTEEA COLUMBIENSIS, Hani. 



Froc. Zool. Soc. 1845, p. 107 : — non Ostrea sp. ind. c, C. B. Ad. 

 Pan. Shells, p. 246, no. 382. 



Shell inside without denticles, of a pure white, resembling a 

 small O. edulis ; hinge area very small. Outside smooth, or 

 with laminai of gro-w th ; light ash, with numerous narrow ray.s 

 of purple. Eather thin, flat, attached by the whole surface. 

 The largest valve (abnormally produced) measures long. 1 ' 55, 

 lat. 1-24. 



Hab. — St. Elena ; adhering to rocks at half-tide ; Cuming. — 

 Mazatlan ; on shells and barnacle-covered rocks, very rare ; 

 L'jiool Col. — Lower California, on Area grandis, Gould's Col. 



Tablet 712 contains a very young pair, detached, and a valve 

 on Imperator unguis. — 713, 2 upper valves. — 714, 2 pairs, very 

 flat and under valve spreading, probably belonging to this 

 species, though approaching some forms of O. Virginica, jun. 



214. OsTEEA COXCHAPHILA, U. S. 



0. t. plerumqiie i^arvu, tenui, suhovali, testis variis affl^xa ; 

 purimred, sape aurantia tiiictd, intenlum racliis una vel duahus ; 

 cardineparvo, utroque latere dentieidis crenato ; area ligam%nti 

 angustd, triangidari, scepizis suleo denticulato titrdque parte 

 extus ornata ; plerumqm totd valvd affixd, margine integro, 

 sed interdiim suhiter ascend^nte, margine undato, vix plicato ; 

 intus suhnacreo, cicatrice modico, irregitlari. 

 ? = Ostrea sp. ind. c, C. B. Ad. Pan. Shells, p. 2-10, no. 382. 



Shell, when delicately grown among Pinna) and Anomije, 

 closely resembling O. bicolor. Hani. fProc. Zool. Soc. 1845, 

 p. 107 -.— Conch. Misc. pi. 1, f 2 : supposed to bo from West 



