1894.] ECHINODEEMS OF ilACCLESFIELD BXSK. 407 



oval. Twelve moiith-papillge to each, angle of the jaw ; a single 

 row of large granules between them and the triangular mouth- 

 plate. Upper arm-plates oblong, much wider than long ; the lower 

 have their distal ends much encroached on bj the side-plates ; the 

 spines are quite stout, and the lowest is long enough to reach the 

 free edge of the plate next in front. 



Colour, when dried or in spirit, pale brown, with eight or nine 

 rings of a yellowish hue at distances along each arm ; bands or 

 patches of a yellowish colour on the disc. 



Diameter of disc 7 mm. ; 6 ; 5. '^ r- . i -• / -S'^- — 



Length of arm 60-5 mm. (broken a little) ; 60 (ca.) ; 50. 



Macclesfield Bank, 13-35 fms. 



Ophiotheix. 



As may be supposed, there were a large number of examples of 

 this genus in the collection ; how many species are represented it 

 is quite impossible to say, but I have determined twelve with very 

 gi'eat difficulty. My experience in this particular is, however, no 

 different to that of any other zoologist who attempts to name 

 specimens of this remarkable genus — unless, indeed, he be one 

 who has no knowledge at all of its peculiarities. No one who has 

 dredged our common British OpMothrix, and has seen how varied 

 are its colours and the characters of its spinulation, will attempt 

 to name exotic specimens with a light heart. It would, of course, 

 be easy enough to do so if one were to take no note of the expe- 

 rience gained by a study of British specimens, for with a few 

 specimens one can always make new species. With considerations 

 such as these before me, it will be no matter for wonder that I 

 have refrained from describing any " new species " from the present 

 collection. To confess the whole truth, I had intended to make an 

 exception in favour of a remarkably coloured and fairly well repre- 

 sented species from Macclesfield Bank. When, however, it was 

 compared with 0. purpurea, with which, indeed, I had at first no 

 idea of comparing it, I found that the new specimens and the old 

 so intergraded that there could be no doubt they were one and all 

 members of an almost protean species. 



It would be worth the while of a student with unlimited 

 leisure — and less, I fear, will hardly do — to work out large series 

 of Ophiothrix. In saying this I shoidd like to add that the late 

 Dr. Brock made a very useful beginning in his essay on " Die 

 Ophiuridenfauna des indischen Archipels"\ 



It has sometimes been supposed that colour is a good guide in 

 the identification of species of this genus. Thus no less an 

 authority on Ophiuroids than Dr. Liitkeu writes : — " Le systeme 

 general de coloration constitue un caractere important qu'il ne 

 faut pas negliger dans la distinction specifique des Ophiothrix " ^. 

 Or, if I may trust myself to translate the fuller Danish text, 



''■ Zeitschr. f. wiss. Zool. xlvii. ; see especially pp. 511 & 516. 

 ^ Danske Vid. Selsk. Skrift. viii. (1869) p. 104. 



