MUSEUM OF COMPARATIVE ZOOLOGY. 85 



from the suture by a smoothish space, marginated by a slightly raised thread ; 

 suture appressed ; spiral sculpture of numerous subequal little elevated re- 

 volving threads with wider interspaces; they are strongest on the summit 

 of the riblets, faint in the interspaces ; there are about five in front of the 

 fasciole and between it and the next suture ; they are fainter on the canal ; 

 transverse sculpture of numerous (on the penultimate whorl 28) narrow, 

 little elevated, slightly oblique riblets, beginning and strongest at the fasciole, 

 and passing over the whorl to fade away on the base ; the thin margin of the 

 suture is sometimes undulated by passing over them ; aperture narrow, long, 

 notch rounded, not deep ; outer lip simple, thin, arched forward, not constricted 

 for the canal ; inner lip simple with a slight callus, thicker at the posterior 

 angle opposite the notcli ; pillar straight, attenuated and somewhat twisted in 

 front, canal wide, slightly recurved. Max. Ion. of shell, 48.0 ; of last whorl, 

 26.5; of aperture, 21.0 ; lat. of shell, 12.0 mm. 



Drillia alesidota var. macilenta Dall. 



Plate XXXVI. Fig. 1. 



Shell more slender, the sculpture more elegant, the spiral element prppor- 

 tionally stronger, existing on the fasciole and canal, as well as over the rest of 

 the surface. Lon. of shell, 36.5 ; of last whorl, 20.0; of aperture, 15.0 ; lat. 

 of shell, 8.2 mm. 



Habitat of type form. Off Cape Hatteras, N. C, in 63 to 107 fms., sand, 

 temperature 67°. to 75°.0 F., at Stations 2595 and 2601 of the U. S. Fish 

 Commission. 



Habitat of var. macilenta. U. S. Fish Commission Station 2417, in 95 fms., 

 sand, 52 miles S. E. of Cape Fear, N. C, temperature 66° F. Station 2402, 

 in the Gulf of Mexico, between the delta of the Mississippi and Cedar Keys, 

 Florida, in 111 fms., mud. Blake expedition, Station 273, in 103 fms , sand, 

 Barbados, temperature 59°. 5 F. 



This is a very plain, simple-looking species of a dull color. It is quite large, 

 but appears not to have been heretofore described or figured. 



Drillia polytorta Dall. 



Plate X. Fig. «. 



Pleurotoma (Drillia) polytorta Dall, Bull. M. C. Z., IX. p. 61, August, 1881. 



Habitat. Off Cape San Antonio, 413 fms. 



This species has much such a sculpture as the last, except that the ribs are 

 larger, rounder, and fewer, the whorls shorter, more numerous, and more 

 inflated. 



