REPORT ON THE CRINOIDEA. 129 



The other species, besides these two which were dredged at Station 214, off tlie 

 Meangis Islands, were Metacrinus costatus, Metacrinus moseleyi, Metacrinus varians, and 

 Metacrinus ivyvillii. As this last also occurred at Station 170, off the Kermadec Islands, 

 it was probably one of those which were coloured dark purple, owing to the presence of 

 acid pentacrinin. Prof. Moseley can give me no clue, however, as to the anomalous 

 form which did not contain pentacrinin at all, but an entirely different colouring matter. 

 It was of a light pink colour when fresh, and when treated with absolute alcohol gave a 

 simple, light red solution, with an absorption spectrum totally different from that of 

 pentacrinin. 



All Prof. Moseley 's spectroscopic observations of the colouring matter of the 

 Pentacrinidse were made in the Pacific ; and it therefore became a matter of some import- 

 ance to determine the presence of pentacrinin in the Atlantic species of the family. For 

 this purpose Prof. Moseley has been kind enough to examine some of the deeply 

 coloured spirit in which there had been preserved several individuals of Pentacriniis 

 ivyville-ilwinsoni that were dredged by the " Porcupine " in 1870, off the coast of Portugal. 

 As might have been expected, the colouring matter proved to be pentacrinin. 



A still more interesting point is the presence of this substance in Holopus. Immersion 

 of a dry, greenish-black Hohpus in alcohol for a few. minutes yielded a diehroic solution, 

 which gave the characteristic spectrum of pentacrinin. It is more than probable, there- 

 fore, that this substance will be found to be present in the four Caribbean species of 

 Pentacrinus. 



Most species of the Comatulse " appear to be either usually of a rose colour or of an 

 orange or yellow, running into a yellow-brown or of a dark purple. Both the rose or red 

 and yellow colouring matters are freely soluble in alcohol, and usually in fresh water." 

 The colouring matter of most of them, like that of Antcdon rosacea, has no characteristic 

 absorption spectrum showing bands. But a dark purple species common at Cape York 

 yielded a special colouring matter which Prof Moseley has termed "Antedonin." It is 

 freely soluble in weak spirit, and gives an intense fuchsin -coloured solution, which yields 

 spectrum consisting of three well defined absorption bands. 



I have little doubt that the species in question was Actinometra strata. Two species 

 of Antedon which were also obtained at Cape York, but in less abundance, seem to have 

 been tinged with the same colouring matter, as their appearance is the same as that of 

 the Actinometra. The most remarkable point about this colouring matter is its presence 

 in a slightly modified form in various deep-sea Holothuriaus. 



(ZOOL. CUALL. EXP. — PART XXXII. — 1884.) li 17 



