40 MOLLUSC A. 
Found by Mr. Couthouy near Orange Harbour, Tierra del Fuego. 
Both this species and H. saxatilis were obtained upon the very 
summit of the highest mountain in the neighbourhood of Orange 
Harbour, about six miles inland, and a mile or more to the north- 
east of the remarkable peak called the Sentry-box. They were found 
exclusively under small, dry stones, about the roots of a species of 
Usnea, which is almost the only vegetation there. None were found 
under stones where there was any amount of moisture. Such as 
were placed in a jar with moist moss died in two or three days, while 
others, tightly enclosed in a dry box with dry moss, continued alive 
and active for a fortnight. They soon closed the aperture with a 
thin, brown epiphragm, but on exposure to the sun, most of them 
began actively to crawl about, though some resolutely adhered to 
their preparation for winter quarters. The epidermis is thick and the 
shell delicate, as is always the case in cold regions. 
The summit where these snails are found has as bleak and desolate 
an aspect as could well be imagined. ‘The rocks are heaped up in 
irregular and jagged masses, and in some places we crossed from one 
to the other on the hands and knees, over narrow ridges composed of 
ragged blocks, which often, as we reached to them for support, rolled 
away down the precipice a thousand feet. The estimated height of 
the peak is 1600 feet; and none of the snails were found on searching 
200 feet below. [1. P. c.] 
It is about the size and colour of H. rupestris, but more depressed, 
and with a less expanded umbilicus. It agrees nearly with D’Or- 
bigny’s H. costellata, from Buenos Ayres (Amer. Merid. 252, part 26, 
f. 6-9), but it is not so large, and the striz are finer. 
Figure 34, animal with the shell; 34a, profile, and 34 0, base of 
the shell, enlarged; 34 c, natural size. 
HEeLix pauxituus (Gould). 
Testa minuta, tenuis, depressa, supra oblique striata, albido-virens, 
infra viridior, sub-polita, perforata: spira anfractibus quatuor sub- 
planulatis ; sutura profunda: apertura circulars ; labro simplict. 
