88 SPOLIA ZEYLANICA. 



sometimes difficult to find. In the specimen referred to above 

 the stone canal was situated close to the third Polian vesicle. 

 The left respiratory tree is larger than the right, but does not 

 extend so far forward as the latter. No Cuvierian organs are 

 present. 



Spicules. — The spicules consist of tables and knobbed 

 buttons. The tables are 72 [>. in diameter, and have a large 

 central hole and several smaller peripheral holes. The margin 

 of the disc is smooth. The tower is 50 [>- high and is robust. 

 Its four uprights are connected by one tier of cross-beams, 

 and the top is surmounted by numerous spines. 



The buttons have three pairs of holes and are 50 [>• long. 



HOLOTHURIA SPINIFERA, Theel. 

 (Plate XIII., fig. 23.) 



Holothuria spinifera, Theel 1886 (42) ; Ludwig 1887 (29). 



Only two specimens of this species have been recorded 

 hitherto, the type of the species which was obtained by the 

 " Challenger," near the Philippine Islands, and one specimen 

 obtained by the Drs. Sarasin on the East Coast of Ceylon. 

 The Colombo Museum possesses three more specimens, two of 

 which were obtained from the Ceylon Pearl Banks by the 

 present writer, and another without a label. One specimen 

 measured when in an expanded condition was 350 mm. long 

 and 65 mm. broad. 



External Clmracters. — The body is yellowish-white on the 

 trivium, with the exception of a light brown streak which runs 

 longitudinally along the medium line. The dorsal surface is 

 light brown, darker in the middle, and becoming lighter at 

 each side. Some of the dorsal papillae are also dark brown in 

 colour. The ambulacral appendages are papillae only. They 

 are scattered irregularly over the body, those on the dorsal 

 surface being bigger and more conical. Along each side of the 

 body at the junction of the bivium and trivium there is a row 

 of papillae slightly larger than those on the back. The bivium 



