36 PHOLADID/E. 



taiiily do so. If we may trust the figures of tlio i)allets, tliis is not 



tlie T. palnmlata of Lamarck, as it was regarded by Forbes and 



Hanley. 



Other specimens of another species of Xijlotrya., about half tlie size 

 of the above, were taken from a specimen of bored 

 timber in tlie collection of the State. It differs also 

 in having no developed posterior auricle, except a 

 mere thickened rim, though there is an internal plate 

 of large size as in X. fimbriata. The pallets have the 

 style proportionally shorter and stouter, and the joints 

 of the blade shorter, more transverse on the concave 



side, and the style traversing the middle of the convex side. 



Oeiitis PIIOLAS, Lin. 1758. 



Shell transverse, gaping at both ends ; hinge margin rolled out- 

 wards and toothless ; a rib-like tooth arises from the cavity of the 

 beaks, and shoots nearly across the shell. 



Shells of this genus are generally found in logs of wood, in stones, 

 or hard clay, which they have perforated ; and they have one or 

 more additional bony pieces on the Ijack of the hinge. 



Pholas costata. 



Shell large, oblong-ovate, white, covered with radiating, toothed ribs. 



Pholas costutn,! AS. Syst. Nat. 1111 (1758). — Gmel. Syst 3215. — Lister, Concli.pl. 

 434, fig. 277. — GuALT. Test. t. 105, fig. G. — Chemn. Conch, viii. 361, t. 101, tig. 

 8G3. — BnuG. Encyc. Meth. Vers. iii. 754, \<\. 169, figs. 1, 2. — Bl.\inville, Malac. 

 pi. 79, fig. 6. — S(nvERBY, Genera of Shells, No. 23, pi. 1 ; Thes. Conch, ii. 487, pi. 

 102, figs. 8, 9. — Lam. An. sans Vert. 2d ed. vi. 45. — Wood, Gen. Conch, pi 15, 

 figs. 1, 2; Index Test. pi. 2, fig. 4. —Adams, Gen. u. 325, ph 89, figs. 1,1a.— 

 Chenu, Man. de Conch, ii. fig.s. 1, 2, 3. — Hanl. Ipsa Lin. Conch. 24. — Tryon, 

 Proc. Ac. Nat. Sc. xiii. 201, where will he fijund a complete synonymy of tlie species. 



Shell large, thin, inflated, oblong-ovate, rounded before and nar- 

 rowed Vtehind, white, covered with radiating ribs, the coarse lines 

 of growth rising over them in an undulating manner, so as to pro- 

 duce tooth-like elevations upon them, at regular intervals ; the inte- 

 rior is marked wnth corresponding indentations. Length six inches, 

 height and l)readth two inches. 



The animal is straw-colored, the tip of the siphons beautifully 

 stipi)led with mahogany brown ; the foot is narrow and long, like 



