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' 5 long, attached to it by its whole length. Another 

 of intermediate size will be found on tablet 20 ; and a valve 

 with Crucibulum. 



Tablet 711 contains a very small Gryphsea-shaped shell, 

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

 of this species. 



213. OSTREA COLUMBIENSIS, Hani. 



Proc. 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 lamina? of growth ; light ash, with numerous narrow rays 

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

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

 lat. 1'24. 

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



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



Upool 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. OSTKEA CONCHAPHILA, n. S. 



O. t. plerumque parvd, tenui, subovali, testis variis affixd ; 

 purpured, scepe aurantid tinctd, interdum radiis und vel duabus ; 

 cardine parvo, utroque latere denticulis crenato ; area ligamenti 

 angustd, triangularly scepius sulco denticulato utrdque parte 

 extus ornatd ; plerumque totd valvd affixd, margine integro, 

 sed interdum subiter ascendente, margine undato, vix plicato ; 

 intus subnacreo, cicatrice modico, irregulari. 

 ? = Ostrea Sp. ind. c, C. B. Ad. Pan. Shells, p. 246, no. 382. 



Shell, when delicately grown among Pinnae and Anomiae, 

 closely resembling O. bicolor, Hani. (Proc. Zool. Soc. 1845, 

 p. 107 : Conch. Misc. pi. 1, f . 2 : supposed to be from West 



