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Show 392 PROF. E. A. MINCHIN ON THE BRITISH [Dec. 13, make such a blunder*, since not only have I found monaxons well developed and abundant in his type specimen, No. 1 of my list below, but it is evident he himself saw them, since he founded one of his usual " connexive " varieties, Asccmdra botryoides. Haeckel further distinguished two varieties, ellisii and solanderii, the former with the " apical ray of the quadriradiates slightly curved, the lateral rays 7 or 8 times as long as thick, the unpaired angle 130°-150°" ; the latter with the " apical ray of the quadriradiates straight, the lateral rays 5 or 6 times as long as thick, the unpaired angle 150°-180°." Since all these variations can be found in any specimen, Haeckel's two varieties may be struck out of the systematic list. As I have also pointed out above, there is nothing in Haeckel's description of Ascandra nitida to separate it from botryoides; A . nitida is, in fact, distinguished from A. botrys by the same characters practically as Ascaltis botryoides var. solaniderii from var. ellisii. Of writers subsequent to Haeckel, Fristedt alone [9] seems to have penetrated Haeckel's mistake, since he calls the species Ascandra botryoides, as Haeckel ought to have done. Fristedt has, moreover, gone a step further, and has put variabilis as a synonym of botryoides, in which he has been followed by Vasseur [23]. I have been sorely tempted to follow Fristedt's lead also, and to place both forms as well-marked varieties of one species, for which, of course, the name botryoides would have to be maintained ; the form ordinarily known as botryoides could then be called botryoides var. typica, and the other botryoides var. variabilis. As has been shown above, the difference between the two forms is purely one of degree in every respect. As regards spicu-lation, they are in complete agreement, every form of spicule occurring in the one being represented also in the other, and the special features of botryoides are merely an exaggeration of those of variabilis. As regards external form, variabilis occurs in a variety of situations and consequently varies in form ; the fact that in botryoides the habits both of situation and growth are constant, is in itself highly suggestive of its being a form-variety adapted to a particular environment. Examination of the sponge brings to light a further very important fact, bearing directly upon the question under discussion, namely, that the thickened triradiate systems so highly characteristic of botryoides are nearly absent, or comparatively scarce, upon the basal network of tubes by which the sponge is attached to its support, but are greatly developed as a protecting and supporting layer upon the erect * The only source I can suggest for Haeckel's error with regard to the monaxons of botryoides is the fact that Uowerbank also failed to see monaxons in this species, and considered their absence as one of the characters distinguishing it from his Leucosolenia contorta. I f my notion be correct, this is a curious case of successive incarnations of an error, manifesting itself first in Bowerbank 1866, then in Haeckel 18/3, and for the last time, let us hope, in Breitfuss 1898. A still more remarkable point in this history is the fact pointed out above, that the specimen from which Bowerbank desciibed the speculation of botryoides was really a specimen of variabilis (Haeckel), while the specimen of " contorta" from which he figured monaxons was in reality a specimen of complicata ! |