﻿2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 59 



inconspicuous, with a very minute prodissoconch, a very elongate 

 narrow lunule and escutcheon present ; the beaks about two-fifths of 

 the total length behind the anterior end. Exterior polished, under 

 a glass showing fine regular concentric striae with wider interspaces ; 

 hinge with about 38 anterior and 48 posterior teeth separated by a 

 small, subtriangular pit for the wholly internal resilium ; pallial sinus 

 wide, rather deep, extending nearly to the middle of the valve ; the 

 total dorsal margin forms nearly a straight line. Length 29, height at 

 the beaks 8, maximum diameter 5 mm. There is a marked anterior 

 and somewhat smaller posterior gape; the greatest height is at or 

 a little in front of the beaks ; the shell is as it were slightly con- 

 stricted behind them. 



The type was collected at station 5850, and is No. 214350, U. S. 

 Nat. Mus. 



ARCA (SCAPHARCA) LIMONICA, new species 



Shell small, white, rounded below, with a straight hinge-line, 

 carrying about sixteen teeth in an apparently unbroken line; beaks 

 low, mesially impressed in a radial sense, situated a little in front 

 of the middle of the shell ; general form rounded quadrate, the area 

 narrow, smooth; surface sculpture of twenty-five squarish, flat-top- 

 ped, narrow radial riblets with much wider interspaces, the latter 

 crossed by little-elevated, concentric, rather distant lamellae more 

 numerous and conspicuous toward the beaks. Length 4.0, height 

 3.5, diameter 2.5 mm. 



Station, with the last. Type, U. S. Nat. Mus. 2 1435 1. 



This little shell has the look of an adult or nearly adult. It is, at 

 all events, apparently not identical with the young of any of the 

 other species obtained from the same beds. 



PITARIA SUBARESTA, new species 



Shell thin, white, somewhat lozenge-shaped, with the prominent 

 beaks at about the anterior fourth; the basal margin produced, 

 anterior and posterior ends attenuated and roundly pointed; lunule 

 cordate, large, nearly smooth, defined by a feeble incised line; 

 escutcheon none ; surface sculptured with rather sharp, narrow, con- 

 centric wavelets, with narrower valleys between ; posterior end a 

 little compressed and tending to rostration. Hinge of the subgenus, 

 the teeth well developed, the hinge-line short ; pallial sinus ascending, 

 pointed above; margin of the valve smooth. Length 28, height at 

 the beaks 23, diameter 15 mm. 



Station 5868. Type, U. S. Nat. Mus. 214352. 



