36 PHOLADlDiK. 



taiiily do so. If we may trust the figures of the pallets, this is not 

 the T. palmulata of Lamarck, as it was regarded by Forbes and 

 Hanloy. 



Other specimens of another species of Xylotrya^ about half the size 

 of the above, were taken from a specimen of bored 



Fig. 3t)2. '- 



timber in the collection of the State. It differs also 

 in having no developed posterior auricle, except a 

 more 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 PHOL.AS, 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 l)ony pieces on the back of the hinge. 



Pholas costata. 



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



Pholas costata, Ias. Syst. Nat. 1111 (1758). — Gmel. Syst. 3215. — Lister, Conch, pi. 

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

 8G3. — Bkug. Encyc. Meth. Vers. iii. 754, pi. 169, figs. 1, 2. — Blainville, Malac. 

 pi. 79, fig. 6. — SowERBY, Genera of Shells, No. 23, pi. 1 ; Tlies. Conch, ii. 487, pi. 

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

 figs. 1, 2; Lidex Test. pi. 2, fig. 4. — Adams, Gen. ii. 325, pi. 89, figs. 1, 1 a. — 

 Chenu, Man.de Conch, ii. figs. 1, 2, .3. — IL\nl. Ipsa Lin. Conch. 24. — Tryon, 

 Proc. Ac. Nat. iSc. xiii. 201, where will be found a complete synonymy of the species. 



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

 rowed behind, 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 with con'es])onding indentations. Length six inches, 

 height and breadth two inches. 



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

 stippled with mahogany brown ; the foot is nari-ow and long, like 



