MUSEUM OF COMPARATIVE ZOOLOGY. 57 



P. (Pleurotomella) Verrillii n. s. 



Shell eleven-whoileil, thin, large, bluish white, with an acute spire and wide 

 twisted canal ; nucleus thin, smooth ; next three or four whorls smooth, shin- 

 ing, with a spiral row of little polished knobs just behind the suture ; thence 

 the entire shell covered with hardly raised spiral flattened threads about equal 

 to the very shallow interspaces, and averaging about four to a millimeter ; the 

 knobs continue in front of the ante-sutural excavation, but in the later whorls 

 have a more pinched appearance ; there are twenty-one on the last whorl ; su- 

 ture appresscd, obscure ; notch broad, shallow, rounded, the ante-sutural band 

 on the last whorl somewhat concave and about four millimeters wide ; lip 

 much produced forward, rounded, falling away toward the canal, which at its 

 anterior end is broad and flaring ; pillar stout, simple with a sharp thin twisted 

 edge and no callus ; aperture equal to half the shell in length and width. 

 Lon. 36.0 ; of last whorl, 25.0. Max. lat. 12.0 mm. 



Station 41, 860 fms. 



This is supposed from the shell characters to belong to Prof. Verrill's sub- 

 genus Pleurotomella, and, so far as his descriptions go, seems not to be identical 

 with any of those described by him alone or jointly with Mr. Sanderson Smith. 

 Whether the subgenus itself can stand will only be determined when the soft 

 parts of the numerous other named divisions of Pleurotoma have been critically 

 examined and compared. Meanwhile it is a convenient receptacle for a few 

 forms which seem to differ in several particulars from those diagnosed in the 

 text-books, or by writers on the subject. 



P. (Pleurotomella?) Sigsbei n. s. 



Shell in general closely resembling the last, with the following diflferences : 

 it has the same number of whorls in 25.5 nmi. length ; it is proportionally 

 more slender ; the knobs are oljlique instead of perpendicular, in the spire 

 are set in the middle of the whorls instead of near the suture, are less promi- 

 nent, and become obsolete toward the end of the last whorl ; there are about 

 eighteen on the last whorl that has them, and they are proportionally more 

 produced than in the last ; the pillar is less twisted and the sharp flaring edge 

 near the anterior end is not so prominent ; the nucleus is smooth and light 

 brown ; the remainder of the shell has a brownish tinge compared with the 

 preceding. Lon. 25.5 ; of last whorl, 15.0; of aperture, 11.75. Max. lat. 

 9.5 mm. 



Station 33, 1,568 fms. Yucatan Strait, 640 fms. (young). 



The spu'al threads in this and the last species cover the ante-sutural band as 

 strongly as any part of the shell. 



P. (Mangilia?) ipara n. s. 



Shell with nine whorls ; nucleus minute, dark brown, polished, smooth ; sec- 

 ond and third nuclear whorls beautifully reticulated Ijy oblique transverse lines 



