168 TESTACEOUS MOLLUSCA. 



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

 crenulated. -^ . . 1|. — JCipixapi. 



* * Rostrated. 



N. Arctica. Srod. Z. J. 4. t. 9. ./. 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 ante7'ior slope forms a sharp elevated ridge 7vhen the valves 

 are closed.^ 



N. NicoBARicA. Larn. A.- — C. /. f. 4. — Reeve, t. 85. f 4. — 

 Arca Pellucida. Ginel 3308.— TF. t. 9. /. 2G.— A. Levi- 

 GATA. D.p. 12,1— Ch.f 541.—^. 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 . .-^q. — 

 Guinea, ^'c. 



N. Pella. Lam. 3.— Son-. G. f. A.—C. I. f. 6.— Reeve, 

 t. 85. /. 6.— Arca P. Lin. 1141 ?—i>. p. 237 l—'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, f . . -J. — Mediterranean. 



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

 t. 9.f 2.—Ch. f. 550, 1.—^. t. 309. /. 7.— N. Rostrata. 

 Lam. 2.— Arca R. Ginel. 3308.— {in part.) D. p. 2A5.—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, h • . H. — Baltic, N. Seas. 



N. MiNTJTA.* Turt. B.p. 178.— Arca M. Ginel. 3309.— 

 Mont. p. lAO. — n. p. 245.— Tr. t. 10. /. 44.— A. Caudata. 

 Bon. 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 A^ery small 



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



