226 Memoirs of the Indian Museum. [Vol. VII, 



These copulatory setae are in length - 61 mm., and in thickness at the middle 

 22/x ; they are almost straight, with a slight curve at the proximal end, tapering 

 and bluntly pointed distally. There is scarcely any ornamentation, — only a few very 

 fine oblique lines, or semicircular markings convex proximally, near the tip 

 (fig. 29). 



There are no penial setae in the segments of the male apertures. 



Remarks : — The above interesting form has obvious relations with those I have 

 previously described (13) under the name Hoplochaetella ; it has, besides the same 

 arrangement of prostates and spermathecae, the same displaced and modified setae in 

 the neighbourhood of the spermathecal apertures, the same distribution of calciferous 

 glands, and the same peculiar nephridial system. It does not however agree in all 

 points with the emended definition of the genus which I gave. 



Of the points of difference, one of the most interesting is the manner of ending 

 of the vasa deferentia ; in the other species of the genus the vasa deferentia unite, 

 and then open in common with the anterior prostate on the seventeenth segment, 

 while here the vasa are separate, and open, one with the anterior prostate on segment 

 xvii, and the other with the posterior on xix. 



In the Megascolecidae, what may be described as an attraction between the ter- 

 minal portions of the genital organs is of very general occurrence. The primitive 

 condition in the family is that known as the " original Acanthodriline/' where the 

 prostates end on segments xvii and xix, the vasa deferentia (after joining together) 

 on xviii, and the spermathecae in furrows 7/8 and 8/9. In the Megascolecinae, one 

 pair of prostates has disappeared, and the other has been "attracted" to join the 

 termination of the vasa deferentia in xviii, an intermediate stage being seen in the 

 genus Diplotrema. In the other species of Hoplochaetella, and in Erythraeodrilus, the 

 conjoined vasa deferentia have been attracted forwards (to continue the same figure) 

 to join the anterior prostatic duct on xvii. In the other species of Hoplochaetella also, 

 the two pairs of prostates are approaching each other, and the two pairs of sperma- 

 thecae show the same tendency. The very frequent union of the original pair of 

 female pores on segment xiv is perhaps to be referred to the same group of pheno- 

 mena. In Eutyphoeus (Octochaetinae) the single vas deferens on each side ends in 

 common with the prostatic duct on xvii. Similar instances can be quoted from the 

 Ocnerodrilinae. 



In the present form, the attraction has taken a different course ; the two vasa 

 deferentia of each side have been as it were pulled apart, one towards the anterior, the 

 other towards the posterior prostate, while these maintain their original position on 

 the middle of segments xvii and xix. 



In regard to the above point of difference, neither the present nor the former 

 species of Hoplochaetella can be said to be primitive as compared with the other ; 

 evolution has merely taken a different course in the two. In certain features how- 

 ever the present form appears .to show a more primitive condition than the species 

 previously described. Thus the two pairs of spermathecal apertures, which in the 

 other species are both on segment viii, are here more widely separated, on segments 



