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Show 2 5 8 DR. W. B. BENHAM ON [N o v . 1 5 , nephridia. But it differs in that the clitelliun in my new species is less than that characteristic for the above. The only difference between Megascolides and Notoscolex upon which Michaelsen lays special stress is the presence of mega-nephridia posteriorly. The diagnosis of the latter genus he gives (p. 187) as : " Chsetfe 8. Clitellum, beginningat or before segment 14, extends over 3| to 10| segments. The female pores are usually 1 pair, seldom unpaired [median]. Spermathecal pores 2 pairs in the inter segmental furrows 7/8 . 8/9 ; rarely shifted backwards on to the 8th and 9th segments. One gizzard in 5 or 6. Plectonephric ; nephridia diffuse. Prostate usually lobate, sometimes tubular." (Italics are Michaelsen's.) The two distinguishing characters, then, are the limited number of spermatheca? and the diffuse nephridia, without the posterior meganephridia. It is unfortunate that in a considerable number, perhaps the majority, of the species included in Notoscolex the condition of the posterior nephridia is unknown. If, then, we depend on these formal diagnoses, we should no doubt refer my new species to the genus Megascolides, especially if they had been found in Australia. On examining the anatomical details of the only species of Megascolides the anatomy of which is thoroughly known, viz. M. australis, we note several differences from Tokea; amongst others : (a) The chsetse are in couples, all ventral. ( b) The prostates are compactly coiled, cylindrical tubes, similar in general shape to those of true Acanthodriline worms; they are, too, situated laterally, and confined to segment 18. (c) The sperm-ducts open into the duct of the prostate in the substance of the body-wall; which is also the case in the only other species of the genus that has been investigated by means of sections, viz. M. illawarrce (see Sweet, p. 113). (d) The spermatheca has quite peculiar rosette-shaped diverticula. But the above statements do not apply to each of the other three species included in the genus ; for the prostates are flattened and more or less lobate ; the spermatheca in M. cameroni is similar to that of many other Cryptodriline species. Nevertheless, in all of them the chfetfe are distinctly coupled ; i. e., the spaces aa and be are greater, much greater in some cases, than ab, whereas in Tokea these spaces are more or less equal and the " coupling " is quite unnoticeable. It is not probable that any of these characters by themselves are of generic value. And, as a matter of fact, when we come to look into the anatomy of these four species we find numerous differences-which, in the case of other genera, Michaelsen has considered as of sufficient importance to deserve generic rank. I refer, for instance, to the fact that M. insignis and M. cameroni have only one pair of testes and this in segment 11. But it is clear that the only characters / |
