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

ECniNODERMATA. 165Arm of the larger specimen about 120, of the smaller about85 millim. long ; in the former the first pinnule is about 20 and thecirri 10 millim. long.Both of the specimens are white and without any dorsal medianline ; dark spots or marks prominently developed on the pinnules.For the present, at least, I associate with A. solans a specimenfrom Warrior Reef, in which the characteristic keel to the pinnuleis developed and iu which the cirri do not seem to have been morothan twelve in number, but in which the number of cirrus-jointswould appear to be less than fifteen.There are also specimens from Port Curtis and Torres Straitswhich, though still small, hardly promise to ever have the stout armswhich are so characteristic of the adult ; further experience will,I think, show them to be " dwarfs."Prom the Arafura Sea we have received a comparatively smallspecimen, which is chiefly remarkable for the smaller number of itscirrus-joints.In Dundas Strait there were dredged some small specimens whichapproach iu character A. pectinata and A. purpurea, but give us,with our present scanty information, but little aid in determiningthe character or limits of these species.From Thursday Island we obtained a somewhat injured and largespecimen belonging to the " type " of A. Solaris, but which completelyeludes my attempts to understand it.Under the name of A. alhonbtuta I was inclined to separate a specimenfrom Albany Island, which is to be distinguished from the formto which the name A. Solaris is ordinarily restricted by the largernumber (20-25) of cirri, and the less prominent keels on the basaljoints of the second pinnules. The general facies, however, of thespecimen is distinctly that of A. Solaris, with the exception of therather remarkable coloration, which has led to the proposal of adistinctive name. When, however, we make a careful comparisonbetween the pattern of this coloration and that of the two specimensfirst described and unhesitatingly referred to A. Solaris, wesee that there is really a striking resemblance between the two, andwe are again led to the reflection that great circumspection is to beexercised whensoever we are tempted to make use of difference incolour as a distinguishing mark. I have already stated that thereare black patches or spots on the pinnules of the first-described pair ofspecitueus ; what we find in the one now under consideration is thatthese spots having greatly increased in number, and become more extensivethan the white, have caused the white ground to assume theappearance of spots on a dark ground. The extreme limit of thespecies seems, however, to be reached by this form ; and as the cirriare more numerous than usual, and the basal joints of the secondpinnule less strongly keeled, I propose to speak of it as A. Solaris^var. alhonotata.We must not be tempted by the diflSculties of specific discriminationto make use of mere coloration : there are in the collection twospecimens of A. Solaris from Thursday Island, one of which is uni-