166 
THE VOYAGE OE H.M.S. CHALLENGER, 
spinous, often witli four larger teeth. Colour in alcohol, whitish, inclining to violet or 
rose. Length of the largest specimen, 140 to 150 mm. 
Habitat. — Station 306a, January 2, 1876 ; lat, 48° 27' S,, long, 74° 30' W,; depth, 
345 fathoms ; bottom temperature, 46°‘0 ; blue mud ; four specimens. Station 308, 
January 5, 1876; lat. 50° 8' 30" S., long, 74° 41' W.; depth, 175 fathoms; blue 
mud; two specimens. Station 311, January 11, 1876 ; lat. 52° 45' 30" S., long. 
V3° 46' W.; depth, 245 fathoms ; bottom temperature, 46°’0 ; blue mud ; several specimens. 
When the animal is fully extended, the body-wall does not seem to present any 
particular thickness along the sides of the body. The dorsal papillae, which are placed 
in a narrow double row only on the dorsal ambulacra, are narrow, elongated, conical, and 
up to 5 mm. long. This arrangement in double rows is far more distinct in the speci- 
mens obtained at Station 311. The position of the pedicels is also more easy to 
distinguish in the specimens just mentioned. When the body is contracted, the three 
series of pedicels seem to be considerably broader. The slightly darker sucking-disks 
measure about 1 mm. in diameter. The warts, which are present on the two lateral 
dorsal interambulacra as well as on the ventral surface, do not form any rows ; they 
are low, of a whitish colour, and mostly attain a greater diameter than the sucking- 
disks of the pedicels ; at first sight one is tempted to consider them as disks of large 
retracted pedicels, but a closer examination shows the falsity of this supposition. The 
pedicels are strengthened by a large perforated terminal plate, surrounded by a few small, 
oblong, perforated, irregular plates and spinous, slightly curved rods. The pedicels 
also contain numerous tables in a more or less deformed state. The warts bear some 
tables near their base, but I cannot find any other deposits in them ; they resemble 
large, flattened disks of pedicels without supporting rods and terminal plates. The 
papillae bear at their top a very rudimentary terminal plate, consisting of an irregularly 
branched network, surrounded by a few transverse slightly spinous rods ; crowded tables 
fill up the rest of the integument of the papillae. The exact number of tentacles is not 
fully stated ; in one individual I counted seventeen. The retractor muscles are, of 
course, absent, and the longitudinal muscular bands simple. 
The shape of the deposits will’ be best understood from the figures (PI. X. figs. 19, 20). 
The diameter of the disk is about 0T7 mm,, and the length of the spire 0‘064 mm. 
The spire, especially in the pedicels and papillae, often terminates in four teeth, and the 
complete though irregularly perforated disks are also more frequent in these positions. 
The animals seem to lack the calcareous ring. A single Polian vesicle, 16 mm. long, 
is present. The dorsal madreporic canal is attached to the dorsal mesentery. A bundle 
of slender, slightly branched genital tubes is situated on each side of the dorsal 
mesentery. Two respiratory trees run out from a common base, and neither of them 
has any more intimate connection with the pseudhsemal vessel system. 
In one of the more complete specimens obtained at Station 311, I have observed some 
