1917.] NATURAL SCIENCES OF PHILADELPHIA. 185 



in the suture. Last whorl is convex above and below the acutely 

 carinate periphery, and a carina also bounds the umbilicus. The 

 peripheral carina has numerous little prominences, inconspicuous 

 and regularly spaced. On the base there are unequal radial wrinkles 

 around the umbilicus. The aperture is somewhat oblique and the 

 peristome projects forward in a point at the periphery. 



Alt. 2.7, diam. 4.5 mm.; diam. of umbilicus 0.9 mm.; 5 whorls. 



The generic place of this species is doubtful. 



Type No. 2832. 



Dentalium sagittarii n. sp. 



The shell is smooth, almost circular in section, but slightly flattened 

 between concave and convex sides, rather strongly and evenly bent, 

 very slowly increasing in size, the greatest diameter contained about 

 twelve times in the length. Not sculptured, but very oblique 

 growth-lines are discernable. 



Length 13, greatest (lateral) diameter 1.1, antero-posterior diameter 

 1 mm. 



This species is more arched than D. macilentum, which is compressed 

 from side to side. D. schumoi differs by its close annulation. 



Leda extricata n. n. 



Leda acuta Gabb, Trans. Amer. Philos. Soc, XV, 1873, p. 25,5. Not of Conrad, 

 1832. 



The shell is rather plump with nearly median beaks and acuminate 

 posterior end, polished, strongly and closely sculptured with even, 

 blunt-edged concentric riblets, equal to their smooth intervals. On 

 the rather large escutcheon, which is indistinctly defined by a slight 

 furrow, the riblets are a little sinuous, slightly emphasized at the 

 sinuation, close and straight near the hinge-line. The lanceolate 

 lunule has a series of short, oblique folds, stronger and more spaced 

 than the adjacent riblets. Rostrum acute, slightly recurved. 



Hinge with long and acute V-shaped teeth, 15 in the anterior, 

 about 20 in the posterior series. 



Length 8.7, alt. 5, diam. 4 mm. 



Type No. 2655, A. N. S. P. 



This abundant species is longer than L. pelteUa DalV with a longer 

 rostrum and quite different lunule and escutcheon. 



Leda pelteUa was based upon (1) the figure of a specimen from 

 Bowden, and (2) L. acuta Gabb not Conrad. As the figure is a more 

 concrete indication than the second reference, we restrict L. pelteUa 



* Trans. Wagn. Inst., Ill, p. q79, PL 32, fig. 5. 



