170 
THE VOYAGE OF H.M.S. CHALLENGER. 
ously thicker. The calcareous ring (Pi. X. fig. 6) is well developed, but in want of 
posterior prolongations. A single ventral Polian vesicle is present. The madreporic 
canal must be very inconsiderable, because I did not detect it in the three specimens 
examined by me. A bundle of rather long, slender unbranched genital tubes is situated 
on each side of the dorsal mesentery, and the long wide efferent duct opens on a small 
papilla, placed anteriorly on the dorsal surface. The longitudinal muscular bands are 
simple and not divided into two bands. Two well-developed respiratory-trees are present, 
running out from a common base, and neither of them seem to be in communication with 
the plexus of pseudhsemal vessels, though the left tree is embraced and held in a proper 
position by some larger “ connecting branches ” of vessels. 
Since the above description was written I have received the two individuals dredged at 
Marion Islands. They agree closely with the specimens obtained from the other Stations, 
and the only difference of importance seems to be with regard to the tentacles, which in 
one of the examples from Marion Island are nineteen in number, but this must evidently 
be considered as a variation. In these two specimens, also, no pedicels are distinguish- 
able in the odd ventral ambulacrum. With regard to the ventral lateral ambulacral 
appendages I am very dubious whether they be papillse or pedicels. In one of the 
specimens they obviously resemble papillse. The dorsal ambulacral appendages, on the 
contrary, bear a greater similarity to pedicels. The arrangement of the ventral lateral 
appendages, whether placed in two rows or more, is not clear. The deposits are 
totally dissolved, excepting in the dorsal pedicels, in which I have seen some fragments 
of spicules. The surface of the skin is covered with small Ascidians, Sponges, Bryozoa, 
&c., which have grown on it. 
Pseudostichopus villosus, n. sp. 
Body oval or elongated, equally rounded anteriorly and posteriorly. Mouth turned 
toward the ventral surface. Anus terminal, ventral, hidden in a rather deep furrow formed 
l)y two vertical folds of the body-wall. Tentacles nineteen or twenty, with numerous, 
crowded minute papillae on the dilated terminal parts. Pedicels numerous, cylindrical 
and minute, often almost imperceptible, especially crowded along the sides of the body. 
Perisome soft and pliable, without calcareous deposits. Colour, lighter or darker brownish. 
Length up to 150 mm. 
Habitat. — Station 146, December 29, 1873 ; lat. 46° 46' S., long. 45° 31' E.; 
depth, 1375 fathoms; bottom temperature, 35°’6 C.; Globigerina ooze; one incomplete 
specimen. Station 147, December 30, 1873 ; lat. 46° 16' S., long. 48° 27' E.; depth, 
1600 fathoms; bottom temperature, 34°'2 ; Diatom ooze; one specimen. Station 
156, February 26, 1874; lat. 62° 26' S., long. 95° 44' E.; depth, 1975 fathoms; 
Diatom ooze; one individual. Station 157, March 3, 1874; lat. 53° 55' S.; 
