94 SPOLIA ZEYLANICA. 



greenish-brown with irregular hght patches and an indefinite 

 dark patch. The lower surface, dark gray with numerous 

 white jjatches. Papillae, on the bivium gray, those on the 

 trivium white. 



Internal Structure. — As in the three previous species the 

 stone canal is exceptionally large, and arises from the right 

 side of the dorsal mesentery. There is a single Polian vesicle. 

 The stone canal is similar to that of the three previous forms. 

 Cuvierian organs are evidently not present in this species, 

 since they are not mentioned by jsrevious writers, and there 

 are none present in the specimens under examination. 



Spicules. — These are very characteristic, and consist of 

 tables and knobbed buttons in the general integument. The 

 knobbed buttons have the usual three pairs of holes and are 

 40 \i. in length. The tables are peculiar in that the tower is 

 supported by numerous uprights. The base of the tower is 

 perforated irregularly and is 90 \^ in diameter. The height 

 of the tower is 85 \x, and the top is surmounted by numerous 

 spines. 



General Distribution. — Indian Ocean, particularly common 

 along the east coast of Africa. 



Remarks. — Herouard (13) expressed the opinion that H. 

 aculeata, Semper, together \^dth H. bowensis, Ludw., and H. 

 modesta, Ludw., should be included in H. albiventer, Semper. 

 Ludwig, Lampert, and Sluiter have rightly shown that 

 H. albiventer differs from all these species in the form of its 

 massive tables. Since the four species described above — 

 namely, Holothuria spinifera, HolotJmria ocellata, Holothuria 

 martensii, and Holothuria albiventer — show such close relation- 

 ship in many respects I append a key to the four species : — 



Common characters. — Ambulacral appendages papillae only, 

 which are situated upon non-contractile eminences. Extremely 

 large stone canal arising from the right side of the dorsal 

 mesentery. 



(1) Tables in general integument having more than four 

 upright supports. Papillae along both sides of body 

 not larger than rest. 

 H. albiventer. 



