168 TESTACEOUS MOLLUSCA. 



very fine transverse striae, the dorsal margin carinated, the keel 

 crenulated. J . . 1 §. — Xipixapi. 



* * Rostrated. 



N. Arctic a. Brod. Z. J. 4. t. 9. f. 1. Oblong, anteriorly 

 subrostrated, the beak slightly recurved posteriorly longer and 

 somewhat rounded ; epidermis thick shining and dark olivaceous ; 

 the delicate lines of growth crossed centrally and anteriorly by 

 strong oblique striae. tV*!^- — Kamshatchka. The edge of 

 the anterior slope forms a sharp elevated ridge when the valves 

 are closed. 1 



N. Nicobarica. Lam. 4. — C. /. f. 4. — Reeve, t. 85. f. 4. — 

 Arca Pellucida. Gmel. 3308.— W. t. 9. /. 26.— A. Levi- 

 gata. D.p. 237.— Ch.f. 541.— E. t. 309../. 8. Transverse, 

 ovate-elliptic, or ovate oblong, anteriorly subangulated, thin, smooth 

 yellowish, pellucid, obtuse at the extremities but anteriorly rather 

 attenuated: margin entire. 1. — Indian Ocean. 



N. Rostrata. Turt. B. p. 178. — Arca R. Mont. Sup. 

 t. 27. f. 7. — D. (in part.) p. 245. Oblong, thin, pellucid, white, 

 smooth, rather gibbous ; posterior side rounded ; anterior acumi- 

 nated, turned upward, with three crenated ridges ; surface covered 

 with oblique nearly longitudinal grooves, margin entire, f . . t 7 q. — 

 Gui?iea, fyc. 



N. Pella. Lam. 3. — Sow. G. f. 4. — C. I. f. 6. — Reeve, 

 t. 85. /. 6.— Arca P. Lin. 1141? — X>. p. 237 1—Ch.f. 546 ?— 

 W.t. 9. /. 27. — N. Striata? Philippi. p. 64. Transversely 

 ovate subtriangular, subequilateral, yellowish olive, thin, pellucid, 

 with regular transverse grooves : posteriorly rounded, anterior 

 dorsal edge but little if at all incurved and forming a sharp angle 

 with the scarcely arcuated ventral. J . . %. — Mediterranean. 



N. Fluviatilis. Sojv. G. f. 3. — Arca F. Schro. Flus. 

 t. 9.f. 2.—Ch. f. 550, \.—E. t. 309. /. 7.— N. Rostrata. 

 Lam. 2.— Arca R. Gmel. 3308.— (in part.) D. p. 245.— W. t. 

 f 43. Transversely oblong, rather convex, thin, transversely 

 striated, posterior side rounded and more than twice as short as 

 the anterior which is attenuated beaked and its very narrow ex- 

 tremity obtusely angulated ; anterior dorsal line nearly straight, 

 oblique : ventral edge rather arcuated. J . . 1^. — Baltic, JV.Seas. 



N. Minuta.* Turt. B.p. 178.— Arca M. Gmel. 3309.— 

 Mont. p. 140. — D. p. 245.— W. t. 10. /. 44.— A. Caudata. 

 Don. t. 78. — Tenuisulcata. Couth, (fide Gould.) Oval, trans- 

 versely striated, white, with three or four concentric ridges, the 

 anterior side produced curved and truncated : beak very small 



1 This is not the Arctica of Gray in Parry's voyage. 



