HOLOTHURIOIDEA OF THE INDIAN OCEAN. 55 



Holothuria utrimquestigmosa, Haacke 1880 (12). 



Several specimens, Trincomalee, Ceylon. Average length 

 150 mm. X 70 mm. 



External Characters. — A massive species with a fairly thick 

 body wall. It is almost cylindrical in shape, slightly flattened 

 dorso-ventrally, and the two extremities are bluntly rounded. 

 The mouth is ventral and the anus is terminal or shghtly 

 dorsal. The colour of the body is auburn-brown, and here and 

 there on the bivium and the sides of the body are irregularly 

 marked deep violet-coloured patches. The ambulacral append- 

 ages are surrounded by small dark patches. The trivium is 

 but little lighter in colour than the bivium. The ambulacral 

 appendages are true pedicels, those on the trivium being 

 slightly larger than the rest. The pedicels are irregularly 

 scattered and very numerous. The anus is more or less 

 pentagonal and is guarded by five groups of papillae. There 

 are twenty light-coloured tentacles. 



Internal Structure. — The calcareous ring is massive, but in 

 the specimens I have examined I do not find that, as Theel 

 states, the calcareous ring is larger than that of H. argus. 

 On the contrary, I find that the latter species has a slightly 

 larger calcareous ring. I am in agreement with Theel in 

 finding a single large Polian vesicle and one stone canal. 

 Lampert has recorded four, five, to seven Polian vesicles, and 

 Koehler (15) has made a point of this difference of evidence, 

 but it is well known that the number of Polian vesicles is a 

 variable character. The right respiratory tree is larger than 

 the left, and the Cuvierian organs arise from the base of the 

 left respiratory tree. 



Spicules. — These consist of a superficial layer of numerous 

 small branched " rosettes " 15 jjt, in diameter. The species is 

 characterized by also having small globular spicules 18 {x in 

 diameter in the deeper layers of the dermis. The pedicles are 

 supported by ordinary rosettes and small H-shaped spicules 

 26 H- in length. 



Distribution. — Shallow water of the tropical zone of the 

 Indo-Pacific region. My own observations show that this 

 species has a peculiarly localized distribution in Ceylon. In 

 Trincomalee it is exceptionally abundant, and I have brought 



