258 DR. W. B. BENHAM ON [Nov. 15, 



nephridia. But it differs in that the clitellum in my new species 

 is less than that characteristic foi- 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. 1 87) as : " Ohsetse 8. Clitellum, beginning at 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 intersegmental 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 spermathecEe 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. anstralis, we note several differences from Tokea ; amongst 

 others : 



(») The chsetee are in couples, all venti-al. 



[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. illaioarroi (see Sweet, p. 113). 



[d) The spermatheca has quite peculiar rosette-shaped diver- 



ticula. 



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 chsetse are distinctly coupled ; i.e., the spaces aa 

 and be are greater, miich 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 sufiicient 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 



