1879.] MR. F. J. BELL ON THE ECHJNOIDEA. 6fil 



bifurcate, so that the two processes thereby formed are longer than 

 in T. angulosus. 



The species of the genus may now be briefly defined : — 



T. angulosus. — Test varying greatly in form and colour, the spines 

 short and generally white ; in the majority of specimens there are 

 well-marked bare spaces in both ambulacral and interambulacral 

 areas ; there are distinct though delicate and short ascending and 

 descending processes connecting each tooth with its alveolus ; and the 

 radii terminate in two shorter processes. The poriferous zones are 

 wider, the actinal system larger, and the anal and abactinal systems 

 more extensive than in T. esculentus. The species has been found 

 in the Red Sea, Mauritius, the Cape of Good Hope, Rodriguez, the 

 Philippines, and at Cayenne. 



T. esculentus. — The test is generally rounded and more constantly 

 white or pinkish in colour; the spines, which are white, are longer than 

 in T. angulosus ; and the median spaces in the ambulacral and inter- 

 ambulacral areas are ordinarily occupied by tubercles of some size ; 

 the pieces connecting each tooth with the alveolus are shorter and 

 more horizontal in direction ; and the two processes of the radii are 

 longer than in T. angulosus, while the poriferous zones are narrower 

 the actinal system smaller, and the anal and abactinal systems less' 

 extensive than in T. angulosus. 



As I have only seen one specimen of T. depressus, it will perhaps 

 be best to leave the statements which I made regarding it as they 

 stand in the body of the paper. 



I append a list of the localities from which the Trustees of the 

 British Museum have received specimens. 



Tripneustes angulosus, Leske. 



a. Gulf of Suez ; with some spines ; pentagonal in shape. 



b. Red Sea. 



c. "Mauritius." 



d. " Isle of France ;" with spines. 



e. Cape of Good Hope ; with spines. 

 /. Isle of Masbate. 



g. Philippines. 



h. Reef of Oomaga ; with spines. 

 i. Rodriguez ; with spines. 

 j. Cayenne 1 . 



Tripneustes esculentus. 



a. Nassau, New Providence, W. I. 



b. West Indies ; with spines. 



Tripneustes depressus. 



a. Gulf of California ; with spines. 



1 This is a most remarkable locality, and I suspect very strongly that it is a 

 slip for Cat/or ; but even iii that case the locality is one from which the species 

 has not yet been recorded. 



