5o2 Mr. C. U. Narayana Rao on the Anatomy of 



ridges appear to be composed of a cord of small spherical cells 

 witli longitudinally disposed muscle-fibres, tije whole of the 

 ridge being compactly held by a thin cuticular pellicle. 

 The entire pouch perhaps represents the greatly modified 

 atrial tubules of Muni/iffuster perrieri — a view which in some 

 measure receives support froai the fact that these ridges are 

 canalised in the case of forms which are just develojiing tlie 

 spermathecal apparatus, and the peritoneal wall enca])snlirig 

 tliem is still thin and devoid of muscle-fibres (Fl. XVIII. 

 figs. 10 A & lOi). The more complete organisation of the 

 peritoneal investment into the atrial pouch must synchronise 

 with the degeneration of the tubes into incomplete ridges. 



The Nejjhridial System. — The vesicle in this species is non- 

 glandular, unlike the other examples described in this paper, 

 and hence has the same structure as that described in 

 D. graudis (PI. X\'I. fig. 5). It is quite transparent, being 

 composed of a few circularly disposed muscle-fibres, and, in 

 the case of anterior somites in the front of the clitelluin and 

 even in some examples behind it, the vesicle opens l)y a broad 

 circular aperture into the respective ccelomic chaii.ber. A 

 glandular vesicle is not, however, uncommon even in this 

 species and then they are white and ])erfectly oi)aque. Tlie 

 i.ephridial lobes and their relation to the other structures 

 are so ditfertnt in this and the other species described in 

 this paper from the figure of D. grandts given by Bourne 

 (pi. xxvii. fig. 42, Q. J. M. Sci. vol. xxxvi.), that a few words 

 respecting the renal organs will not be inappropriate here. 

 The two vesicles form nearly a complete ring round the 

 alimentary canal, almost meeting dorsally, but extending 

 only halfway ventrally below the intestine. From the lower 

 half of its stem is given ott' the slightly coiled muscular duct, 

 which runs outwards to o})en on the seta-line cd. Among 

 the glandular lobes we recognize the twisted and the looped 

 ones. There are two of the former kind, one being longer 

 than the other, both ventral to the aliment;, ry canal, and the 

 longer tuisted lobes on each side are only separated by 

 tlie nerve-cord. There are three looped lobes : two of them 

 are in close relation to the sides of the alimentary canal on 

 the inner side of the vesicle, and the third more or less 

 attached to the muscular tube, and hence on the outer side 

 of the vesicle. The funnel-tube enters the main glandular 

 mass at the point where the inner looped and the twisted 

 lobes diverge, and the duct of the funnel-tube also divides, 

 entering rcsjiectively the two main divisions of the nephridial 

 structure. In regard to the histological structure of the 

 diti'erent parts, excepting the nephrostomc, which is same as 



