REPORT ON THE HOLOTHURIOIDEA. 
227 
Habitat . — Navigator Islands (Semper). 
(Mus. Holm.) One specimen from the Na^dgator Islands. The ambulacral appendages 
being retracted, it is very difficult to distinguish the difference between the 
pedicels and papillae ; possibly the latter have a smaller terminal plate and 
more numerous rod-like supporting rods. The buttons are sometimes furnished 
with eight holes instead of six. 
Holothuria immobilis, Semper, 1868. Holothuria collaris, Haacke, 1880 (according 
to Ludwig). 
Ventral surface with pedicels ; dorsal surface with papillae. The disks of the tables 
spinous. The buttons irregularly formed, with about six holes. Tentacles 
twenty-eight to thirty. 
Habitat . — Philippine Islands (Semper), Mauritius (Haacke, Ludwig). 
According to Semper, the deposits resemble those of Holothuria pardalis, consequently 
the spire of the tables terminates in eight to ten teeth. 
(Mus. Holm.) One specimen dredged at the Navigator Islands. Length, 155 mm. 
Colour — ventral surface dirty yellowish-white, especially anteriorly, inclining to 
brown ; dorsal surface brown with darker spots or bands ; papillae and tentacles 
almost white. Tentacles twenty-six. Anus with some papillae. The spire of 
the tables is short but well-developed, and its annular top carries eight to ten 
or more teeth. The disks bear distinct spines round the margin, and are 
perforated with a larger central almost quadrangular hole and several smaller 
peripheral ones. The buttons are more or less asymmetrical, typically with 
six holes, but often with fewer. The papillae are provided with a rudimentary 
terminal plate and with curved rods which are generally enlarged and perforated 
at the ends. The pedicels have a well-developed terminal plate, a few rods 
and perforated bilateral plates. Two very long Polian vesicles. A bundle of 
about ten small madreporic canals present on the right side of the dorsal 
mesentery, and only two such canals placed on the left side. 
Holothuria ccesarea, Ludwig, 1875. 
Pedicels all over the body excepting towards the extremities, where papillae are sub- 
stituted for pedicels. Deposits like those in the preceding species. Tentacles 
thirty. 
Habitat . — Navigator Islands (Ludwig). 
Further investigations will doubtless prove that there exists no specific distinc- 
tion between the three forms above mentioned, but that they represent the 
same species, which, however, may be capable of variation in several 
respects. 
