170 TESTACEOUS MOLLUSCA. 
the specimen before me three or four granular lines radiate down 
the posterior slope. 
N. Recurva. Conr. Jour. A. N. S. Phil. 6. t. 11. fi. 21. 
Oblong, concentrically striated towards the beaks, and obliquely 
so towards the ventral edge: anteriorly rostrated and recurved, 
posteriorly rounded, beaks subcentral. +.— West Indies. 
N. Sapotritna. Gould. Mas. p. 100. f. 61. Elongated 
ovate, translucent, subequilateral, posteriorly rounded, anteriorly 
narrowed and compressed; the anterior dorsal edge straight and 
rendered sharp by the compression of a very narrow portion of the 
margin; subrostrated, tumid at the beaks with only a slight 
flexure under the anterior tips; smooth, polished, pale yellowish 
green: teeth about sixteen on each side. #..5%,.—North 
America.® 
N. Navicuutaris. Couthouy. Bost. Journ. N. H. 2. t. 4. 
f.4.— Gould. Mas. p. 103. Small, smooth, fragile, subequilateral, 
greenish yellow, posteriorly rounded, anteriorly feebly beaked ; 
slightly truncated, ventral margin very convex; beaks prominent ; 
inside white and glossy, the hinge with from sixteen to eighteen 
teeth. 1.— North America. 
N. Nasuta. Sow. in Conch. Il. f. 12.—Reeve. t. 85. f. 12. 
Oblong, white, very finely striated transversely ; posterior side 
rather shorter than the anterior, rounded: anterior acuminated, 
slightly turned upwards, with an elongated transversely striated 
dorsal area. %..4.—Last Indies. 
N. Fasuta. Sow. Conch. II. Ff. 13.— Reeve. t. 85. f. 138. 
Ovate, white, obliquely striated, nearly equilateral, posterior side 
rounded, anterior acuminated, slightly turned upwards, with two 
ridges passing from the umbones to the acuminated extremity, the 
upper of which is crenated, forming an anterior dorsal area. 
eae) 
ee 
N. Srriata. Sow. Conch. Il. f. 16.—Reeve. t. 85. f. 16. 
Ovate, white concentrically striated, nearly equilateral, the dorsal 
slopes nearly equal; posterior side slightly acuminated, rounded ; 
anterior side acuminated, with an indistinct dorsal area. 2..43.— 
China. 
N. Maurirtana. Sow. Conch. Ill. f. 17.— Reeve. t. 85. f. 17. 
Ovate, white, concentrically grooved, nearly equilateral, posteriorly 
rounded, anteriorly acuminated: dorsal slope nearly equal on both 
sides. }.. 2.—Mauritius. 
N. Limarunta. Say. Am. Conch. t. 12.—Gould. Mas. p. 98. 

1 Add likewise the N. Guaciauis. G'ray. in W.S. t. 2. f. 6. 
2 See too the Myauis of Couthouy in Boston. J. of N. H. 2. 
t. 3. f. 7.— Gould. p. 99. 
