EEPOET ON THE HOLOTHXJEIOIDEA. 
183 
Holothuria Jactea, n. sp. (PL X. figs. 9 and 15). 
Body elongated, oval. Mouth turned towards the ventral surface. Anus almost 
terminal. Tentacles small, twenty. A simple row of pedicels along each side of the 
ventral surface. The odd ambulacrum naked. Dorsal surface with small, very much 
scattered papilla-like prominences. Perisome soft and pliable, containing numerous 
crowded delicate tables consisting of a large rounded or stellate disk pierced by six very 
large boles arranged round a small central hole, and bearing a strongly constructed 
central spire built up of three rods and one transverse beam ; the spire terminates in 
three very long smooth teeth. Colour, milk-white. Length about 110 mm. 
Habitat . — Station 78, July 10, 1873 ; lat. 37° 26' N., long. 25° 13' W.; depth, 1000 
fathoms; volcanic mud; two fragments. Station 169, July 10, 1874; lat. 37° 34' S., 
long. 179° 22' E. ; depth, 700 fathoms ; bottom temperature, 40°'0 ; blue mud; a single 
indhddnal. 
The ventral surface is evidently flatter than the dorsal, and does not bear any other 
ambulacral appendages than the simple row of pedicels along each side. These pedicels, 
only about twenty in each row, are not closely crowded but placed at some distance 
from each other, and measure about 8 mm. in length ; their ends are slightly enlarged, 
the pedicels thus accpiiring a clavate appearance. The terminal plates of these pedicels 
are not very well developed. The enlarged ends of the pedicels are strengthened by 
numerous crowded, almost smooth, more or less curved, transverse, unbranched rods. 
The pedicels also contain more or less deformed tables in great abundance. The 
very minute papilla-like 'dorsal ambulacral appendages are few and scattered ; besides a 
rudimentary terminal plate and a great number of more or less deformed tables, they 
contain a few curved spicules. The twenty tentacles are small and seem to terminate in 
about four processes. The perisome is filled up by tables (PI. X. fig. 9) which have a 
very characteristic shape. The disks of these tables have a very fine conformation, and 
their circumference is either rounded or stellate with six angles ; they are pierced by six 
large peripheral holes and a small central hole ; the diameter of the disks is about 0'2 mm. 
The spire (PI. X. fig. 15, h) is more firmly constructed, and attains a length of about 
0‘24 mm.; it consists of three rods joined near the base by a transverse beam; from the 
apex, where the three rods are united, three long, slender, smooth, divergent teeth 
arise. In the pedicels and papillae especially the disks of the tables are more or less 
deformed. A single short Polian vesicle is present. The small madreporic canal is 
attached by its tubercle to the dorsal body-wall in its middle line. The reproductive 
organs are situated on the left side of the dorsal mesentery, and consist of several genital 
tubes, each terminating in a bundle of short slightly branched sacs, within which the 
eggs are visible. The longitudinal muscular bands are. simple and without retractors. 
Two wide and well develoj^ed respiratory-trees are present and do not seem to be in any 
