PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 327 



Only a few specimens have been taken off Martha's Vineyard, at sta- 

 tions 892 and 894, in 487 and 3G5 fathoms, 1880; station 947, in 312 

 fathoms, 1881. 



This little species bears some resemblance to B. decussata, bnt can be 

 readily distinguished by the much finer and more uniform sculpture. 



Bela incisula Verrill. 



f I'leurotoma Trevelyana, var. Smlthii Jeffreys, Ann. and Mag. Nat. Hist., 1876, 



p. 332 («ott Smilhii Forbes). 

 Bela impressa-i Verrill, Proc. U. S. Nat. Mus., iii, pp. 365, 1880 (won Morch.). 

 Bela iwcisuZa Verrill, Trans. Conn. Acad., v, p. 461, pi. 43, fig. 12; pi. 57, fig. 14. 



The shell is small, subfusiform to short ovate, with about five or six 

 turreted, flattened whorls, which are angularly shouldered just below 

 the suture. The subsutural band arises abruptly from the suture, 

 nearly at right angles, and its surface is flat or slightly concave, 

 marked by strongly recurved lines of growth, but mostly without spiral 

 lines. The shoulder is often nearly right-angled. The whorls are 

 decidedly flattened in the middle. There are, on the last whorl, about 

 twenty rather broad, flattened or rounded ribs, which are nearly 

 straight, a little prominent and usually slightly nodose at the shoulder, 

 but they disappear a short distance below it. They are separated by 

 well excavated, concave grooves, deepest close to the shoulder. 



The most characteristic feature of the sculi3ture is that the surface is 

 marked by rather fine, but regular and distinct, sharply incised, narrow, 

 revolving grooves, which are rather distant, with flat intervals. Of 

 these there are usually about three to five on the penultimate whorl, 

 and about twenty to twenty-eight on the last, the greater unmber being 

 below the middle, on the siphon, where they become coarser and closer, 

 with narrower rounded intervals. One of the sulci, just below the 

 shoulder, is usually more distinct, and cuts the ribs so as to give their 

 upper ends a subnodiilous appearance ; below this there is usually a 

 rather wide zone, without grooves; usually no revolving Hues above 

 the shoulder. The apex is usually eroded ; when perfect it is acute. 

 The nucleus has a very small and slightly j)rominent, smooth apex; its 

 first turn is marked with fine spiral lines; the next whorl has, at first, 

 about three stronger, spiral, raised cinguli, which soon begin to be 

 crossed by thin transverse riblets. 



Aperture about half the length of the shell, narrow ovate, or ellipti- 

 cal, angulated above. Canal short, nearly straight, a little narrowed 

 at the base by an incurvature of the lip. The outer lip has a decided 

 angle at the shoulder, below which the edge is well rounded, and pro- 

 jects strongly forward, in the middle; the sinus, above the shoulder, is 

 rather deep, wide, and evenly rounded within. Columella strongly 

 excavated in the middle, obliquely receding at the end. 



The shell is commonly greenish white and covered by a thin, close, 

 greenish epidermis; but some specimens are clear white, rarely pinkish. 



Ordinary specimens are about e.S'"'" long; 3.5"^™ broad; apeiture, 



