NATURAL SCIENCES OP PHILADELPHIA. 475 



Teredo grcgata, Deshayes, Note in 2d edit. Lam. Ann. sans. Vert., vi. p. 39. 



Fistulana gregaria, Blainville, Diet. Sc. Nat., p. 83. 



Serpula retorta, Mawe, Conch., t. 34, f. 5. 



Teredo nucivorus, Spengler, Skrivt. Nat., ii. pt. 1, p. 105, t. 2, f. d. Catlow, 

 Conch. Nonienc, p. 3. Cuvier, Regne Anim., ed. Audouin, t. 114, f. 4. 

 Deshayes, Traite Elem., t. 2, f. 1518. Dillwyn, Disc. Cat., p. 1090. 

 Jay, Catalogue, 4th edit., p. 9. 



Ilab. Tranquebar, Pondichery, etc.* 



Coll. Acad. Nat. Sciences. 



Description. Valves covered by a brown epidermis, solid in texture, very 

 convex, narrow, being two and one-half times longer than their width ; in 

 this respect differing very much from the other species of the family. Ante- 

 rior auricle extending about one-third the total length, with its basal margin 

 very oblique and long, and its dorsal margin short and declining ; lateral an- 

 terior side sharply angulated by the junction of the dorsal and basal margins. 

 Posterior auricle very small, consisting of a mere triangular lateral swelling 

 of the margin, appearing in some specimens like a tooth. Beaks very narrow, 

 much raised, and tuberculate. 



Internally the fang is deeply and narrowly channelled from the beaks to 

 the ventral tubercle. Apophysis very oblique, curved, turning to the poste- 

 rior side. Anterior to the central channel the substance of the valve is much 

 thinner. 



Externally the anterior area is marked by a few rather coarse concentric 

 strife. Anterior to the centre of the fang and opposed to the internal channel 

 is a corresponding longitudinal raised rib, which is rather closely transversely 

 striated ; posterior to the rib the surface is nearly smooth, with the exception 

 of a few longitudinal strife, visible on the posterior shoulder. 



Length ^ inch ; breadth not quite th inch. 



Pallets about J inch in length, the blade exceeding the style ; blade spoon- 

 shaped, concave on one side, convex on the other, and thickened on the con- 

 vex side to a little above the middle, whence it is depressed to the tip ; the 

 depressed area is covered with elegant ribs whieh radiate to all parts of the 

 upper margin, causing it to be toothed. 



Tubes singularly contorted and twisted upon themselves, a mass of them 

 frequently growing together, they are of a light brown or yellowish red color, 

 and very solid, rapidly acuminating from the rounded base to the upper end. 



Length four inches ; breadth at base three-fourths of an inch, at tip half 

 as much. 



Genus XYLOTRYA, Leach. 



Xtlotrya, Leach, MSS. (subgenus.) Adams, Genera, ii. p. 333. Gray, Zool. 

 Proc. p. 188, 1847. Gray, Ann. and Mag. Nat. Hist. 2d ser. viii. p. 381. 

 Jeffreys, Ann. and Mag. Nat. Hist. 3d ser. vi. p. 125. Menke, Syn. 

 Meth., 1830. Sowerby, Illust. Brit. Shells. 



Xylotrya, Quatrefages r Ann. des Sc. Nat. 3d ser. xi. p. 28. 



Bankia, Gray. 



Teredo, (part.) Blainville, Diet. Sc. Nat. lii. p. 259. Blainville, Malacol. p. 

 579. Bosc, Hist. Coq. ii. p. 197. Catlow, Conch. Nomenc. p. 2. Chenu, 

 Man. ii. p. 12. Cuvier, Regne Anim. edit. Griffith, xii. p. 123. Delle 

 Chiaje, Mem. iv. Deshayes, Encyc. Meth. p. 1002. Fischer, Journ. 

 Conchyl. 2d ser. i. Forbes and Hanlev, Brit. Moll. i. p. 58. Hanley, 

 Desc. Cat. p. 3. Home, Phil. Trans.," 1806. Lamarck, Anim. Sans. 

 Vert. edit. 1, v. p. 438 ; et edit. 2, vi. p. 35. Lamarck, Syst., 1801. 

 Philippi, Enum. Moll. Sicil. i. p. 2, et ii. p. 3. Spengler, Skrivt. Nat. 

 ii. pt. 1. Schumacher, Essai d'un Nov. Syst. Thompson, Ann. and 

 Mag. Nat. Hist., 1847. Turton, Conch, dithyra, p* 13. 



* The specimen in Coll. A. N. S. is marked " St. Croix, W. I.," doubtless a mistake. 



1862.] 



