50 



BULLETIN m, UNITED STATES NATIONAL MUSEUM. 



differs b}?^ having- the umbo of the carina removed from the .summit, 

 by the shape of the tergum and the presence of a minute rostrum. 



Besides several examples from the type locality, in the Caribbean 

 Sea, two specimens were taken at a station north of the Bahamas. 

 These differ from the types by their smaller size — the larger having 

 a capitulum 11 mm. long— and by the weaker radial stride, which are 

 ver}^ minute. (Fig. 15.) 



SCALPELLUM SINUATUM, new species. 



Ti/j)e.— Cat. No. 9013, U.S.N.M. 



Type-locality. — Albatross Station 2037, east of Maryland, north lati 

 tude 38° 53', west longitude 69° 23' 30", in 1,731 fathoms, bottom 

 temperature 38° F. 



The capitulum is trapezoidal, about twice as long as w^ide, with 

 slightlv curved occludent border, and of a pale 3^ellowish-white tint; 



not hairy; valves 14, nearh' smooth. 



The scutum has a convex occludent mar- 

 gin. The lateral margin is produced in a 

 point at the tergal end, excavated below 

 it. The basal margin is somewhat con- 

 vex. 



The scutum is of the usual triangular 

 shape, with convex occludent margin and 

 narrow, slightly recurved apex. There 

 is a slight prominence on the carinal mar- 

 gin above the carina. 



The carina is long, arcuate, with apical 

 umbo. The roof is flat between two mod- 

 erate rounded ribs. The sides are rather 

 FIG. i6.-scALPELi.uM SINUATUM. a, b, wldc abovc, tapcrlug to the base. 

 ofxvPE, iN^o.^rYouNrxoPo^vPE^ The uppcr lateral plate is subtriangu- 

 ^^^^^- lar, with a deep notch in the lower mar- 



gin. The scutal margin is decidedly longer than the tergal. Mucro at 

 the scuto-tergal angle. 



The rostrum is very small, subtriangular, lying between the um- 

 bones of the rostral latera. 



The rostral lateral plate is quadrangular, nearly as high as wide, but 

 with the basal margin shorter than the scutal. The lateral margin is 

 convex. 



The inframedian lateral is wineglass shaped, narrowest at the lower 

 third. The upper portion is triangular, its upper face concave, 

 against the upper latus, but one angle extends up, touching the 

 scutum. The umbo is median. The base of the plate is expanded, 

 forming a smaller triangle than the upper part. 



