68 
THE VOYAGE OF H.M.S. CHALLENGER. 
seems to be common to several forms of the genus in question. The specimens dredged 
at Stations 295 and 298 are totally devoid of deposits, the calcareous substance having 
probably been dissolved. 
The integument is thin, often transparent. The calcareous ring resembles that in 
Cucumaria abyssorum, but appears narrower. The Polian vesicle and madreporic canal 
are single. The muscular stomach is not very well developed. The reproductive organs 
as well as the respiratory-trees are more highly developed than in the species itself. 
Cucumaria abyssorum, var. hyalina, nov. (PL IV. fig. 7). 
Body subcylindrical or fusiform, slightly curved, more tapered posteriorly. Tentacles 
ten, of almost equal size. Anus surrounded by some small papillae and more strongly 
developed, tooth-like deposits. Pedicels arranged in a double row along each ambu- 
lacrum, slightly more numerous on the ventral than on the dorsal surfaces. Integument 
thin, glassy, and very rough from scattered, rather large four-armed deposits, resembling 
those in Cucumaria abyssorum, but provided with a long, spinous, outwardly directed 
process. Pedicels strengthened by terminal plates and transverse supporting rods 
almost like those in the species just named. Colour, white, transparent. Length 
up to 30 mm. 
Habitat . — Station 147, December 30, 1873; lat. 46° 16' S., long. 48° 27' E.; 
depth, 1600 fathoms; bottom temperature, 34°'2; Diatom ooze; three specimens. 
Station 300, IDecember 17, 1875 ; lat. 33° 42' S., long. 78° 18' W.; depth, 1375 
fathoms ; bottom temperature, 3 5° '5 ; Globigerina ooze ; two specimens. 
Though this variety bears the closest resemblance to Cucumaria abyssorum, it is 
easily distinguished by several obvious characters. The posterior extremity of the body 
is not so evidently tail-like. The pedicels are more numerous and the integument is 
transparent glassy, and much rougher with the outwardly directed processes of the 
deposits visible to the naked eye. The characteristic four-armed deposits (PI. IV. 
fig. 7) are scattered and distinct from those in the above named species by the presence 
of a rather large and spinous, outwardly directed process, running out from the base of 
one of the arms or from the central part of the deposits itself. Often that arm, which 
carries the spinous process, is shorter than the rest. The ends of the arms are 
commonly pierced by one to four holes, seldom by more. In less developed deposits 
the ends of the arms are completely devoid of holes, simple or provided with some 
minute branches. The diameter of the deposits measures as much as 0‘4 mm. It may, 
however, be remarked that even in Cucumaria abyssorum the deposits show a tendency 
to develop such outwardly directed spines. The pedicels are supported by terminal 
plates and transverse supporting rods almost like those in the above cited species. 
From scanty materials I cannot give any detailed description of the papillae and 
