REPOET ON THE HOLOTHUEIOIDEA. 
169 
Genus Pseudostichopus, n. gen. 
Tentucles nineteen or twenty. Amljulacrcil appenduges in tlie shape of pedicels 
alone (?) ; those on the ventral surface not arranged in the three longitudinal series 
characteristic of Stichopus. Tw o bundles of genital tubes present. Anus without teeth, 
but hidden in a distinct vertical furrow. Deposits unknow-n. Eectractors absent. 
Pseudostichopus mollis, n. sp. (PL X. figs. 5, 6). 
Body more or less elongately oval, ecjually rounded anteriorly and posteriorly. 
Mouth almost completely ventral in position. Tentacles twenty. Anus ventral, hidden 
in a rather deep furrow formed by two vertical folds of the perisome. Pedicels very 
minute, present only on the paired ambulacra ; the odd ventral ambulacrum seems to 
be naked, if pedicels really exist, they must be very rudimentary. Pedicels of 
the dorsal surface arranged in a narrow double row along each ambulacrum, those of 
the lateral ventral ambulacra being more crowded and, as it seems, placed in two to 
five (?) rows. Calcareous deposits of the perisome absent. Colour in alcohol, light 
yellowush-white. Length, 140 mm. 
Habitat . — Station 309a, January 8, 1876 ; lat. 50° 56' S., long. 74° 14' W. ; depth, 
140 fathoms; blue mud; six specimens. Station 311, January 11, 1876 ; lat. 52° 
45° 30' S., long. 73° 46' AY.; depth, 245 fathoms; bottom temperature, 46°'0 ; blue 
mud; numerous specimens. Station 144a, off Marion Island, December 26, 1873 ; lat. 
46° 48' S., long. 37° 49' 30" E. ; depth, 50 to 75 fathoms; bottom, volcanic sand; two 
specimens. 
Though I cannot find any deposits in the perisome, it seems very likely that 
such w^ere present in the living animals, and, consequently, that they have been 
dissolved in the Challenger specimens by the influence of some acid. From the want 
of deposits as well as from the minuteness of the pedicels in general, a very careful 
examination is necessary to be convinced of the presence of these pedicels, which are 
almost indistinguishaljle from the exterior of the body. At first sight therefore one 
is tempted to consider the animals as belonging to the apodous Holothurids. For the 
same reasons I cannot positively state the absence of pedicels in the odd ambulacrum; 
sometimes I thought I observed some rudimentary ones. It is also almost impossible to 
tell the true shape of the ambulacra! appendages, but, to judge from some small ones 
which I saw extended, they are probably pedicels and not papillae. The vertical 
furrow in the posterior extremity of the body appears to be characteristic of the forms of 
this genus (PI. X. fig. 5). The tentacles are retracted within the body and their processes 
retracted, but, as far as I can see, they must be allied to those present in the 
Aspidochirotae. 
The body -wall is soft, thin, and pliable ; along the sides of tbe animals it is inconspicu- 
(ZOOL. CHALL. EXP. PART XXXIX. — 1886.) QT ^2 
