46 
THE VOYAGE OE H.M.S. CHALLENGER. 
other nearly related genera. Now, Ludwig ^ recently proved that the species of Brandt 
is identical with Ckirodota discolor, Eschscholtz, and he also expressed the opinion that 
the whole genus Liosoma must be annulled. There is no doubt that Trochostoma 
albicans agrees most strikingly with regard to the shape of its tentacles with Liosoma 
arenicola, but at the same time its similitude to the genus Trochostoma being in all other 
points very obvious, I have thought myself justified in referring it to that genus. In 
conformity with the views of Ludwig, it appears to me that the genus Liosoma is founded 
on very secondary characteristics. 
Trochostoma albicans, var. glabra, nov. 
Habitat. — Station 169, July 10, 1874; lat. 37° 34' S., long. 179° 22' E.; depth, 
700 fathoms ; bottom temperature, 40 ’0 ; blue mud ; a single individual. 
Length of the individual, 115 mm. Colour in alcohol, whitish. The only difference 
existing between the type and its variety, as far as I know, is that .the integument of 
the latter is almost smooth, the calcareous deposits being more scattered than in the 
former. The tentacles also seem to differ in some degree, their comparatively broad 
ends sending out on each side a very inconsiderable process, beneath which another pair 
of minute processes is visible. 
Trochostoma sp. (?). 
Habitat. — Station 299, December 14, 1875 ; lat. 33° 31' S., long. 74° 43' W.; 
depth, 2160 fathoms; bottom temperature, 35*2 ; blue mud; one specimen. 
The calcareous deposits of the integument being in a state of dissolution, no 
description of their true form is possible. Only posteriorly in the caudal portion of the 
body are deposits left, exhibiting a shape almost identical with that common in Trocho- 
stoma arcticum, Trochostoma boreale, &c. They consist of a perforated disk with two 
arms, one on each side, and a central crown made up of three or four processes, which 
are mostly completely dissolved. No coloured deposits are to be seen. Possibly other 
forms of deposits have existed, though they are dissolved by some impurity in the 
alcohol. The tentacles are fifteen, retracted, each provided with, as it seems, two small 
processes. All the internal organs resemble those in the before mentioned species. 
Colour jn alcohol, whitish, inclining to violet. Length about 85 mm. 
Trochostoma (?). 
Habitat. — Station 309, January 8, 1876; lat. 50° 56' S., long. 74° 15' W.; depth, 
40 to 140 fathoms ; blue mud ; fragment of one individual ; its generic as well as specific 
position were impossible to determine. 
’ Eevision der Mertens-Brandt’schen Holothurien, 1881, pp. 581-583. 
