416 Rfc V. R. BOOG WATSON OK THE 



rectilinearly curved ; its edge, on leaving the body, retreats im- 

 mediately to the left to form the shallow rounded open sinus 

 which occupies the shoulder below the suture. Below this it 

 advances with a long oblique forward slope in the line of the 

 riblets, and then, from about the middle, retreats on a very- 

 regular curve to the point of the pillar. Inner lip is a thin glaze 

 with a defined edge ; it is very narrow on the body, but spreads 

 round the pillar ; it is convex on the body, with a bluntly angular 

 concavity at the base of the pillar, which is short, small, conical, 

 unequal-sided, obliquely cut off in front, with a narrow rounded 

 twisted edge. H. 0*61. B. 03. Penultimate whorl, height 01. 

 Mouth, height 0*31, breadth 0*19. 



This is a peculiar form, stamped essentially with the charac- 

 teristics of a frigid- water species. 



20. Plextrotoma (Drillia) flttctuosa, n. sp. 



St, 149 d. January 20, 1874. Lat. 49° 28' S., long. 7.0° 13 ' E. 

 Royal Sound, Kerguelen. 38 fms. Mud. Var. cariosa, W. 



St. 151. February 7, 1874. Lat. 52° 59' 30" S., long. 

 73° 33' 30" E. Heard Island. 75 fms. Mud. 



Shell. — High, broadish, conical, with a shortish conical base, a 

 slight angulation near the top of the whorls, very oblique ribs, 

 rather thin, white. Sculpture. Longitudinals — below the sinus- 

 area narrow, close-set ribs make their appearance so abruptly as 

 almost to count for tubercles ; they bend very obliquely to the 

 right, and correspond with the lines of growth with which the 

 surface is closely puckered ; on the base they coalesce and become 

 faint, disappearing wholly on the snout. Tiiere are twenty-three 

 on the last whorl ; in number, but hardly in size, they diminish up 

 the spire rapidly ; the hollows between them are about as broad as 

 the ribs. Spirals — in the sinus-area, and between the ribs where 

 the epidermis is preserved, there are fine, sharp, close-set, minute 

 hair-like threads, somewhat fretted by the lines of growth ; on 

 the summit of the ribs these also appear, reticulating the surface, 

 but are less distinct ; below the sinus-area there is an angulation 

 arising almost entirely from the prominence of the rib-ends. 

 Colour dull porcellaneous white below the pale yellowish-grey epi- 

 dermis, which rubs off all the prominent parts of the shell. Spire 

 conical, but with its profile-lines much broken by the contraction 

 at the sutures ; its upper part is small and rather cylindrical. Apex 

 globose, round, comprising two embryonic whorls, the extreme 



