JAMES A. GRIEG. [SEC. ARCT. EXP. FRAM 



Trichotropis bicarinata, BRODERIP & SOWERBY. 



(Figs. 4-8). 

 Locality: 



July 22. 1900. The winter harbour, Havnefjord, about 60 ra. Small stones. A 

 rather damaged specimen measuring: total height 30 mm., largest 

 diameter 24 mm., length of aperture 17 mm., breadth of aperture 

 13 mm. 



The shell (fig. 4, a 6) is quite thin, translucent, white and covered 

 by a skin-like wrinkled dirty yellowish-white epidermis. Sculpture con- 

 sists of close, fine, oblique, longitudinal lines. Fine spiral striae are 

 also visible under the microscope. Number of whorls 6, of which the 

 last is decidedly ventricose. The apical whorls are white, smooth and 

 convex. The last whorl is furnished with two sharp spinal carinae, 

 which are densely covered with large well-develoved setae. The penul- 

 timate whorl has a setiferous spiral carina. The two remaining whorls 

 seem also to be furnished with spiral carinae, but it was impossible to 

 examine them closely owing to their being covered by a sponge. Aper- 

 ture is sub-circular and somewhat more than half the length of the shell. 

 Umbilicus deep and partly covered by the columella, which is excurved 

 and has a slight indication of a canal at its base. On the outer side 

 the umbilicus is bounded by a sharp carinae, which like the spiral 

 carinae is thickly covered with setae. Operculum (fig. 4 c) is triangular 

 (5 X 6.5 mm.) and of the same form and structure as in trichotropis 

 hjorti, FRIELE. Radula also resembles that of this species. 



The specimen belongs apparently to the variety trichotropis tennis 

 from Grinnell Land described by SMITH: though SMITHS specimen, which 

 was of about the same size (33 mm.), appears to differ from it in having 

 a more slender and more tapering spire, and further does not seem to 

 have such well-developed setiferous filaments on the spiral carinae or 

 on the umbilical carina. This latter carina moreover in the Fram speci- 

 men is placed in a position more resembling that of trichotropis bicari- 

 nata BROD. & Sow. (Cf. Tryon : Manual of Conchology, vol. 9, tab. 7, 

 fig. 42). The whole appearance of the specimen too reminds one not 

 only of trichotropis tennis but also of trichotropis bicarinata, and 

 I am accordingly most inclined to accept the view of JEFFREYS that 

 trichotropis tennis is a monstrous variety of the last-named. 



We must also include trichotropis hjorti, FRIELE as a variety of 

 trichotropis tennis, a fact I have already alluded to in the report on 

 the "Belgica" expedition of 1905. This form was first discovered in 

 1900 by the Norse Fishery Steamer "Michael Sars" in the cold area 



