GASTEROPODA. 219 
about five on the upper whorls, and about sixteen on the principal 
whorl. In some parts the furrows seem to be crossed by delicate bars. 
The interspaces are flat. There are five whorls, which have a dis- 
tinct, square shoulder; the large whorl is tumid, the upper one plane. 
The aperture is lunate, about three-fifths the length of the shell. The 
columella, about one-third the length of the aperture, is flat, and 
divided by a single groove. 
Length of axis one-fourth of an inch ; breadth one-sixth of an inch. 
Dredged off Patagonia. 
This little species, like T. puncto-striata and T. venusta, to which 
it is allied, has not the ivory surface of most species. It is well cha- 
racterized by its form and sculpture. 
Figures 263, 263 a, dorsal and ventral views of the shell, enlarged ; 
263 5, natural size. 
TRICHOTROPIS CANCELLATA, Hinps; Proc. Zool. Soc., London, 1843. 
Zoology of the Voyage of the Sulphur (Mollusca), 39, pl. 11, f. 11, 12. 
AntmMaL much as in Littorina, Planaxis, and Melania, but the snout 
is on a line with the tentacles, and not much protractile. Mouth large 
and corneous; tongue as usual; no retractile proboscis. Eyes near 
the outer base of the tentacles; “ verge’ exposed on the right side, 
near the tentacle. Foot tumid in front, capable of adhering pretty 
firmly to glass. Margin of the mantle slightly scolloped to correspond 
with the ridges of the shell. Colour pale, as though not much ex- 
posed to the light. Motion sluggish. (C. Pzckering.) 
The operculum is narrow-ovate, sub-spiral, with the apex dentate. 
The shell is twice the size of the specimens figured in the Voyage 
of the Sulphur, which were obtained from Sitka, while ours were 
from the Straits of De Fuca, where they are abundant. ‘They were 
at least an inch in length. The epidermis is bristled with long fila- 
ments as in Triton. By age the umbilical slit becomes obliterated 
