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

166 COLLECTIONS PKOM MELANESIA,foruily purple, while the other has the purple relieved by a whitemedian dorsal line and by some white pinnules.I trust that with an increase in our knowledge and with a largerseries of specimens the preceding discussion will be found, long as itmust have seemed, to be of some aid in the determination of thecharacters and limits of the species ; with such scanty informationas we possess at present it would be to the last degree rash toventure on any kind of prophesj-. Were I to make one, however,I should say that many of the variations, which at present there isa tendency to regard as of specific importance, will be found topresent less constancy of arrangement when large series are broughttogether for examination. In the work of enlarging our knowledgeof the species of Crinoids the British Museum may well look tothose English colonists who live on such sea-boards as that of theAustralian coasts, and who have opportunity to do some dredgingin their waters.The student will believe that it was not without much study thatI instituted the species now succeeding ; since I did so I have hadthe opportunity, thanks to the kindness of Mr. E. P. Eamsay, ofexamining a collection of Australian Echinodcrms ; and it was ^^'itha certain amount of satisfaction that I obtained from it specimenswhich exhibited a close resemblance to A. intermedia, and led meto think that I was justified in -regarding its differential charactersas constant and definite.Standing midway between A. soJeiris and A. rohusta it may bedistinguished as17. Actinometra intermedia.As Mr. Carpenter has pointed out, it appears to be possible, inpart at any rate, to distinguish A. Solaris from A. rohusta by thecharacter of the keels, which, in the former, are so strikingly developedon the basal joints of the second pinnule. Basing myself onthe theory that the keel is constantly present on the basal joints ofthe second pinnule of A. Solaris (Plate XVI. fig. A, a), and that it isnever found on those of A. rohusta (fig. A, h), I venture to think that,in the case of A. intermedia, we have to do with a form in whichconstantly the keels are never as well developed as in A. Solaris,and never so slightly as in A. rohusta, while at the same time thereare considerable differences in the extent of the development of thekeel, not only within the limits of the species but even of the individual(cf. figs. A, c, d).The following appear to be the more characteristic marks of thespecies :—A general resemblance to A. Solaris ; but there are about18 cirri, with from 18-20 joints ; first pinnules not specially long,of rather more than 40 joints ; basal joints of second pinnuleswith a not conspicuous keel, and with one which varies in theextent to which it is developed. Arms widest a slight distancefrom the disk.