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Show 812 MR. F. E. BEDDARD ON [Nov. 3, Lumbricus and three species of Megascolex in a paper published in the 'Transactions of the New-Zealand Institute'1; but as that author has merely referred to external characters, it is impossible to speak with certainty as to the identity or non-identity of the species which 1 propose to describe in the present paper with any of his. The practical impossibility of distinguishing species of Earthworms from each other by external characters only is so well known to those who have occupied themselves with the anatomy of the group, that I need scarcely insist upon it here. When, however, the relations of external characters to internal structure are known, something may be said about the systematic position of an Earthworm from its external characters, though, speaking generally, it would be unsafe to assign it to any particular genus without dissection. As far as we know at present, the genus Acanthodrilus can be so distinguished ; the four male generative apertures on or in the neighbourhood of the sixteenth and eighteenth segments, each with the penial setee protruding, are distinctive of Acanthodrilus. After reading carefully Hutton's description of his four species of New-Zealand Lumbrici, I am inclined to think that three at least do not fall within the genus Lumbricus as at present defined and understood ; these are L. uliginosus,L. campestris, and L. levis. In all the clitellum occupies from five to six segments situated in the anterior region of the body between segments 10 and 25 ; the " male genital apertures" are stated to be on the 9th segment (L. campestris), the 9th and 10th (L. uliginosus), or upon the 10th to the 15th (L. levis). The "vulvae" are upon the last two segments of the clitellum. It is possible that L. levis is the type of an altogether new genus, but the other two species appear to me to belong to the genus Acanthodrilus. What Captain Hutton, following Hoffineister, terms "vulvee" are, I should imagine, the male genital apertures, while his "male genital apertures" may be the orifices of the sperma-thecse. If m y suppositions are right as to the meaning of the terms used in Hutton's descriptions, there is every probability that L. campestris and L. uliginosus are representatives of the genus Acanthodrilus, more particularly since this genus undoubtedly does occur in New Zealand, as will appear from my own descriptions. On the other hand, the fourth species of Lumbricus (L. annulatus) described by Captain Hutton does really seem to belong to the genus Lumbricus, as far as one can judge from its very incomplete definition. To the three species described in the present paper I give new names, because they appear, so far as I can make out, to differ specifically from those described by Captain Hutton ; they may prove, however, to be identical ; a comparison of types can alone settle the question. The three species which I am now about to describe clearly differ from each other sufficiently to warrant.their separation as distinct species. I have regarded them all as belonging to Perrier's genus Acanthodrilus, because they possess four male generative apertures each furnished with a prostate gland. The only other genus known 1 Vol. xi. p. 317 ; see also vol. ix. p. 350. |