491 



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

 Pro. Zool. Soc, 1849. 



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

 trali subangulata; costis laqueatis coucentricis ornata; postice 

 laevigata, subattenuata ; laminis dorsalibus quatuor, parvis. 



A small, globose species, differing from Ph. Teredinaformis in 

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

 dorsal laminae. 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. Teredinaformis. 



Floating 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 subcyKndrica, ventricosa, magna, in partes tres oblique 

 divisa ; parte antica prope marginem ventralem sublsevigata, dorso 

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

 mide crassa induta ; parte postica oblique triangulari, transverse 

 epidermide laminata, ad terminum truncata ; margine ventrali in- 

 tegumento diviso, elongato, corneo, celato ; margme dorsali 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 laminge in reHef. The ventral margin is 

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

 margin by another, the anterior part of wliich 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 Bey, California. Mr. Eartweg. 



21. Pholas Inch (pi. cv. f. 45, 46), Sowerhy, pmr., Pro. 

 Zool. Soc, 1849. 



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

 divisa; parte antica prope marginem ventralem sublsevigata, 

 dorso usque ad mediiun minute longitudinahter et transverse 

 striata j 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 elongatas, integras. 



