222 
THE VOYAGE OF H.M.S. CHALLENGER. 
ambulacral appendages, and by having some darker transverse bands on the back. 
Even here the deposits of the pedicels and papillae are considerably more developed 
than in the body-waU itself, though the tables never seem to attain the unusual 
length of the spire, nor to have the great number of transverse beams. 
Holothuria arenicola, Semper, 1868. Holothuria maculata {Sporadipus, subgenus 
Acolpos), Brandt, 1835 ; Ludwig, 1881, 
Pedicels all over the body. The tables have the smooth disk pierced by a larger 
central hole and several small peripheral ones ; their spire is built up of four 
rods and one transverse beam, and terminates in several teeth. The oval buttons 
regularly with six holes. 
Habitat . — Philippine Islands, Amboina, Fiji Islands, and Surinam (Semper), Bonin - 
sima (Brandt), Mauritius (Haacke, Ludwig). 
(Mus. Holm.) One specimen brought home from the Navigator Islands. Length, 
100 mm. Colour — light yellowish-grey, with a row of distant darkish-brown 
spots along each dorsal ambulacrum ; also some minute scattered spots. Anus 
surrounded by five groups of small papillse. Tentacles very minute. Calcareous 
ring of the usual shape. Two Pohan vesicles and a bundle of three small 
madreporic canals on the right side of the dorsal mesentery. The tables greatly 
resemble those in Holothuria impatiens, but they have not the nine nearly equal 
holes in the disk, which on the contrary is perforated by a large central 
hole and a varying number of small peripheral holes. The spire terminates 
in twenty or more teeth. The buttons are very symmetrical, as a rule 
with six holes. Considering that the ambulacral appendages, which have a well- 
developed terminal plate, are quite retracted within the body- wall, it is uncertain 
whether they really are pedicels. The supporting rods of these pedicels are 
smooth, slightly enlarged, and perforated at the middle and the ends. The 
species is probably very nearly related to the preceding one, and distinguish- 
able from it only by the shape of the buttons. 
fi. Disks of the tables spinous on the margin and more or less developed. Number of 
tentacles typical, twenty. 
Holothuria signata, Ludwig, 1875. 
Dorsal surface with scattered papiUse ; ventral surface with pedicels arranged in three 
longitudinal series. Tables with rudimentary spinous disk and the top of the 
narrow spire rounded, devoid of spines. The oval buttons with two to four 
holes, two considerably larger; several developmental stages of the buttons 
not rare. 
Habitat . — Tahiti (Ludwig). 
