TRIBE ARCACEA. 169 
with a smooth dorsal area reaching thence to the anterior ex- 
tremity.— England. 
N. Parva. Sow. in Conch. Ill. f. 7.—Reeve. t. 85. f. 7. 
Oblong, white, thickish, with an olivaceous epidermis, transversely 
grooved; posterior side rounded, anterior rather beaked, angular : 
dorsal area anteriorly not grooved. +3,..%.—WN. Pole. 
N. Pouira. Sow. Z. P. 1832.—C. I. f. 11.— Reeve. t. 85. 
f. 11. Oblong anteriorly beaked, white under a polished greenish 
epidermis, anterior dorsal edge, smooth; with some oblique an- 
terior strie. 9,.. 144.—Panama. 
N. Cosrenuata. Sow. Z. P. 1832.—Con. Il. f. 238.— 
Reeve. t. 85. f. 8. Oblong, thin, covered with small concentric 
acute riblets; anteriorly beaked and acuminated, with two dorsal 
approximated and crenulated ribs. 1..4— Panama. 
N. Grezosa. Son. Z. P. 1832.—Reeve. t. 85. f. 9.—Con. 
Il. f. 9. Oblong, gibbous, anteriorly acuminated and beaked, 
_ transversely grooved; anterior dorsal edge depressed, with the 
central margin elevated. 3..14.—Peru. 
N. Exvenensis. Sow. Z. P. 1832.—Reeve. t.85. f. 14.—Con. 
Il. f. 14. Ovate, gibbous, transversely grooved, anteriorly acumi- 
nated and beaked; anterior dorsal margin arcuated, the margins 
crenulated. {,..4.—W. Colombia. 
N. Esurnea. Sow. Z. P. 1832. Ovate gibbous, transversely 
grooved, glossy, ivory-like, anteriorly acuminated and _ beaked. 
gy--43.—W. Colombia. 
N. Cuneata. Sow. Z. P. 1832.—Reeve.t. 85. f. 15.—Con. 
Il. f. 15. Ovate, wedge-shaped, gibbous, concentrically grooved, 
the epidermis greenish, glossy, the posterior side rounded the 
anterior acuminated. }..2.—Valparaiso. 
N. Turéca#rormis. Storer. Bost. J. of N. H. 2.—Gould. 
Mas. f. 66. Large, oblong ovate, gaping at both ends, posteriorly 
rounded and shorter, anteriorly broader and obliquely subtruncated 
so that the dorsal extends further than the ventral edge; a rib-like 
wave passes from the beaks to the ventral anterior angle: cuticle 
dark olive green: hinge witha very large spoon shaped tooth on each 
side of which are twelve teeth, each one folded from the centre to 
an angle of forty-five degrees : inside polished white. 143.,24.— 
North America. 
N. Ergutsit. Couthouy Annals Lyceum, N. H.—Say. Cat. 
t. 1. f. 12, 3. Subelliptical, glossy, convex, moderately thick, sub- 
equilateral, posterior side rather longer; anterior side very slightly 
and obtusely rostrated ; ventral edge entire, much arcuated; dorsal 
edges but little sloping, the anterior subincurved, the posterior con- 
vex: cuticle blackish olive, marked only by the prominent lines of 
rowth ; no anterior depression: inside dull bluish white; hinge 
broad, teeth few and obtuse, cardinal pit triangular. +..14.—Jn 
