igoy.] Records of the Indian Museum. ' 247 



specimens ; the variability in amount and distribution of this 

 granular matter being perhaps correlated with the fact of its being 

 here a " rudimentary organ," 



What may be called the " buccal nerve commissure " does 

 not appear to have been described in other species of Chcetogaster ; 

 but here again C. diastrophus shows a related condition, the oesopha- 

 gus being surrounded at its middle by a ganglionic ring. In 

 C. cryUaUiniis (Vejd.) a similar ring surrounds the anterior end of 

 the oeiophagas ; and the condition in C. pellucidus may be derived 

 from this by supposing a still further forward shifting of this ring, 

 which now takes origni from the commissures at the sides of the 

 buccal cavity ; as might be expected on the supposition of the 

 homology of these structures, the fibres of the buccal commissure 

 of C. pellucidus are derived from the ventral side, not from the 

 cerebral ganglion. 



Tne gemtal hairs and genital setae seem worthy of note. The 

 latter appear to be modified in a direction contrary to what is 

 Uiual ; tiiey abort to some extent, and cease to project. Since in 

 this form the normal setae (and the same is the case in C. punjab- 

 ensis) project ventrally in a vertical direction, with little or no 

 lateral inclination, they could, if retained, only be a hindrance to 

 copulation, and their abortion probably allows a closer appositiom, 

 necessary in the case of aquatic forms. 



As to the segments in which the reproductive o-^gans are con- 

 tained, the ovaiy is evidently in the sixth segment ; as, being at 

 the level of the setae of this segment, is also the opening of the vas 

 deferens. The anterior portion of the vas deferens and the testis 

 may, following the rule for the genus, be supposed to lie in the 

 fiftn segment, though there is here no means of fixing segmental 

 limits. As previously said, the receptacula appear to be in the 

 fourth segment ; this is unusual in the Naididae, and it may possibly 

 be the case that the septa in front and behmd the oesophagus are 

 septum |- and ^ respectively, not f and |- as I have assumed ; in 

 tnis case the cesopnagus would occupy the fourth, not the third 

 segment, and the pnarynx both second and third, there being 

 then no septum between the second and third segments. My 

 numbering of the anterior segments of C. punjabensis would also 

 in tnis case require revision. 



Tne aosiiije of a chtellum, and the development of the sper- 

 matozoa Wxiile doating in tne Oody-cavity are noteworthy. 



On thjJ Indian Species of the Genus CfLErooAsxER. 



Michaelsen (Oligochaeta) in 1900 enumerates five species of 

 Chaetogaster, all fro^n Europe, Annandale, in describing C, ben- 

 galensis, mentions that the genus has also been found 111 America, 

 referring, pernaps, to C. gulosus, Leidy, 1852, which Michaelsen 

 calls doubtful, and of wnich he gives no description. Within 

 the last two years five species have been recorded from India, so 

 that the extent of the genus has been doubled. The new species 



