Report on the zoological collections made in the Indo-Pacific Ocean ...

ECHINODERMATA, 1257. LincMa marmorata.Ophidiaster marmoratus, Michelin,Mag. Zuol. 1845, Zooph. p. 21, pi. 10.Liuckia marmorata, Perrier, p. 13o.If I am correct in referring to this species a series of specimensfrom Port Molle and Fitzroy Island, it will be easy to understandhow it is that M. Michelin's species was never again recognized tillthe Paris Museum came into the possession of his type ; that wouldappear to be the only example that they possess, and, as M. Perrierpoints out, the " typo " is obviously young. The specimens beforeme are clearly enough all representatives of the same species ; butwere any one of them described it is quite possible that from thedescription alone of that single specimen it would be easy to regardsome others of the series as belonging to another form.In the first place, though all the specimens are provided with theintermediate plate that connects into a pentagon the terminal one ofthe " ranges de plaques qui occupe la ligne mediane dorsale dechaque bras," the extent to which this is evident varies a good deal,and one would hardly think it worthy of especial note in the largestexample were not attention directed to it by the better-markedcharacters of some of the smaller. Secondly, the smallest specimenhas the dorsal plates covered with coarse granulations ; of some ofthese, at any rate, it would be appropriate to say (again quotingPerrier) " les granules voisins de leur centre sent un peu plus grosque les autres;" on the other hand, one, two, or more granulesnear the centre acquire, in the larger specimens, a much greaterpredominance, and give a somewhat different appearance to thecreature ;in the largest specimen these again have disappeared, andthe whole surface of the plates is more uniformly granular. Thirdly,the dorsal plates may lose the regularity of outline which is so wellmarked (if not exaggerated ?) in Michelin's figure, and which isexpressed by M. Perrier in the words " sensiblement carree," andbecome narrower at the angles at which the pores are placed ; thisis perhaps due to the greater development in the number of pores,of which as many as seven may in some cases be found within thelimits of one area. Lastly, it is only in the smallest specimens thatwe find a double row of tubercles fringing the adambulacral spines ;in aU the larger specimens the row is single, or, in other words, onerow of tubercles ceases to grow proportionately, and becomes obscuredin the general granulation of the actinal surface.The only considerable point of difference between these specimensand that figured by Michelin lies in the remarkable coloration ofhis specimen ; if, however, M. Desjardin's example from the islandof Mauritius was immediately dried, it might have retained its colour :while Dr. Coppinger's specimens, which were placed in spirit, mightvery possibly have had part of their colouring-matter dissolved out.The largest example has E equal to 50 miUim.Prince of Wales Channel, 7 fms.