148 CEYLON PEARL OYSTER REPORT. 



SOME NOTES ON THE ABOVE-NAMED COLLECTION 



OF ECHINODERMS. 



BY 



F. JEFFREY BELL, M.A., 



EMERITUS PROFESSOR AND FELLOW OF KING'S COLLEGE, LONDON. 



I had the advantage of going through the eleutherozoic actinogonidiate Echinoderms 

 with Professor Herdman himself, and lie has included my determinations in the above 

 list. The more difficult specimens I brought to London for determination in the 

 National Collection, and on these, and on some general aspects of the subject, I take 

 leave to say a few words. 



(l.) The collection contains a large number of specimens of common Indo- Pacific 

 Echinoderms and a goodly store of young forms ; these it is most necessary to keep 

 with their generic allies ; the determination of their species is quite a trivial matter 

 as compared with the importance of obtaining a rich and extensive series of stages, 

 showing the variations due to increase in size, and also the numerous individual 

 variations which wide-spread species of Echinoderms always exhibit. 



(2.) The absence of some of the species which at present we are inclined to associate 

 with Ceylon, such as Asthenosorua urens, Fromia lumida, Ophiothela holdsworihi, is 

 to be deplored, but the general character of the collection leads us to suppose that 

 these species are local even in Ceylon ; the presence of Opliiopteron elegans, which 

 Mr. Stanley- Gardiner obtained in his expedition to the Laccadives, confirms me in 

 my view that this species is widely distributed in the tropical waters of the Indian 

 Ocean. 



(3.) On one important matter I have at last some hope that we are on the way to a 

 solution. In 1887 the late P. M. Duncan* observed " One of the commonest species 



of the Ophiurida is a form which is usually found without a top to the 



disk," but the fact, apart from the difficulty it produced as to naming the genus, did 

 not appear to him to be of any interest. 



In 1888"j" I somewhat pointedly drew attention to the same phenomenon, and I 

 ventured to remark, " Naturalists who have the opportunity of observing this long- 

 armed form in life should direct particular attention to this loss of the disk, with a 

 view to answering such questions as to whether the loss is in any way associated 

 with the act of reproduction, whether the disk becomes restored, and, if so, whether 

 the restoration is effected rapidly." 



* ' Journ. Linn. Soe. Zool.,' vol. XXL, p. 90. 

 t ' Ann. and Mag. Nat. Hist.,' p. 368. 



