180 
THE VOYAGE OF KM.S. CHALLENGER. 
disks have quite a smooth margin, and the number of holes seems, as- a rule, to be nine. 
The buttons (PI. VII. fig. 9, d) are smooth and mostly regularly formed with six holes 
in two rows ; their length is about 0‘08 mm. The rods in the pedicels (PI. VII. fig. 9, e) 
have commonly the form given on the plate. A bundle of very large, unbranched 
Cuvierian organs, about 50 mm. long, is present. 
The specimen obtained at the Sandwich Islands mainly differs in its uniform brown 
colour and in the smallness of its slightly darker coloured warts. 
Holothuria vagahunda, Selenka, 1867 (PL VII. fig. 10). 
Habitat . — Tongatabu (Friendly Islands) ; one individual. Samboangan (Philippine 
Islands) ; one individual. Fiji Islands ; a single specimen. 
I am in great uncertainty with regard to the ambulacral appendages of the dorsal 
surface, they may be considered either as pedicels or papillae. Some of them have a more 
or less obviously conical form and resemble papillae, others are more cylindrical ; a closer 
examination proves that the former are devoid of ' a true sucking-disk, have the terminal 
plate very rudimentary and the walls strengthened by numerous spinous transverse rods, 
while the latter have a small though distinct sucking-disk, a much larger terminal plate 
and comparatively few supporting rods ; these rods are only collected around' the terminal 
plate, and are not distributed over a greater space as is the case in the papillae, and, like 
those in the ventral pedicels, they generally resemble elongated plates with two more or less 
incomplete rows of holes, or bilaterally symmetrical, fenestrated, more or less elongated 
plates. Evidently, then, the dorsal ambulacral appendages are of two kinds, viz., 
pedicels and papillae.. The ventral appendages are slightly more- numerous than the 
dorsal ones ; in the specimen* from Tongatabu they seem to be much more numerous 
and crowded ; this, however, depends upon a higher degree of contraction of the ventral 
perisome. 
The colour of the individual from the Philippine Islands is pale brown, while the 
specimen from Tongatabu is darkish brown. I cannot with certainty state the number 
of tentacles which are fully retracted within the body, but I believe there are eighteen in 
the specimen from Tongatabu. A single madreporic canal is present. The individual 
from Tongatabu is provided with three Polian vesicles, while the other has only one 
or two. Cuvierian organs of a reddish-brown colour are present. The deposits 
obviously resemble those in the typical Holothuria vagahunda ; scattered among the 
common tables with the wide annular apex of the spire provided with eight to ten teeth, 
others are found with their spire much more tapering towards the apex, which becomes 
very narrow and comparatively inconsiderable. The disks of the tables (PI. VII. 
fig. 10, a) are often uneven in the margin and even spinose, but there are also many 
disks to be found which have the margin rounded, smooth, and slightly undulating. The 
