491 



19. Pholas aperta (pi. cviii. f. 99, 100), Somerby, junr., 

 Pro. Zool. Soc., 1849. 



Ph. testa globosa, aperta, in medio divisa ; antice margine ven- 

 trali subangulata ; costis laqueatis concentricis ornata; postice 

 laevigata, subattenuata ; laminis dorsalibns quatuor, parvis. 



A small, globose species, differing from PJi. Teredinqformis in 

 having the posterior end longer, and in having two pairs of small 

 dorsal lamina?. Being found in mahogany, the shell has a dark 

 reddish tint. In other respects it is subject to the same remarks 

 that are applied to Ph. Teredinceformis. 



Moating wood, Straits of Sunda and Banca. Cuming. 



20. Pholas Californica (pi. cii. f. 5, 6, 7), Conrad, Ann. 

 Nat. Sc. Phil. i. p. 236. t. 18. f. 4. 



Ph. testa subcylindrica, ventricosa, magna, in partes tres oblique 

 divisa ; parte antica prope marginem ventralem sublawigata, dorso 

 usque ad medium imbricatim costato ; parte media plana, epider- 

 mide crassa induta ; parte postica oblique triangular!, transverse 

 epidermide laminata, ad terminum truncata ; margine ventrali in- 

 tegumento diviso, elongato, corneo, celato ; margine dorsab integu- 

 mento triplicato, elongato ad umbones, angustato, celato. 



A very large shell, with the surface of each valve divided into 

 three parts : the anterior part, ventrally smooth, dorsally costated ; 

 the intermediate part plain ; the terminal part, with the epidermis 

 forming transverse laminae in rebef. The ventral margin is 

 covered by a long, divided, folded integument, and the dorsal 

 margin by another, the anterior part of which is bilobate on each 

 side, and the posterior part is elongated and trifold. The speci- 

 men figured (half the natural length) is in Mr. Cuming's collec- 

 tion. Mr. Metcalfe possesses one, not so perfect, but about five 

 inches long. 



Sandstone, deep water, Monte Key, California. Mr. Hartwerj. 



21. Pholas Inch (pi. cv. f. 45, 46), Sowerby, junr., Pro. 

 Zool. Soc, 1849. 



Ph. testa subcylindrica, brevi, ventricosa, in partes tres oblique 

 divisa; parte antica prope marginem ventralem sublsevigata, 

 dorso usque ad medium minute longitudinaliter et transverse 

 striata ; parte media plana, epidermide crassa induta ; parte pos- 

 tica oblique triangulari, epidermide in laminis serratis producta ; 

 margine dorsali integumento in partes quatuor diviso, quarum duas 

 anticas breviusculas, duas posticas clongatas, integras. 



