966 MR. H. K. MEHRA ON TWO ISiEW INDIAN 



of only one sperm-sac, which in appearance and structure is quite 

 similar to that in the ISTaididae ; the anterior sperm-sac, which is 

 present in many Tubilicids is not present here. The main 

 portion of the body-cavity in segment 6 or 9 is cut off from a 

 peripheral portion, and forms the central chamber, which contains 

 all the organs and is filled with the developing sperms — a peculiar 

 feature of this genus. That the worms do not reproduce 

 asexually by budding, which is a common occurrence in the 

 Naididas, separates them sharply from that family. There ai-e, 

 however, some features in which Aulodrilus shows a simplicity of 

 structure comparable to that met with in the Naididse, e. g. in the 

 vascular system, where the presence of hearts in the 6th segment 

 in A. kashi^ and the absence of supra- and sub-intestinal vessels 

 and integumental network is noteworthy ; the brain also is with- 

 out a median lobe, and there are no giant nerve fibres in the 

 ventral nerve-cord. 



The distinct Tubificid characters are as follows : — • 



(1) Structure of efferent apparatus with an atrium and massive 

 prostate followed b}^ a long convoluted atrial duct enclosed in the 

 muscular or ccelomic sac, 



(2) Constant presence of a large ovary throughout the sexual 

 phase. 



(3 ) The large massive prostate is connected with the atrium as 

 in Tuhifex and some other Tubiflcids. It appears to be developed 

 as an outgrowth of the atrial epithelium. 



(4) Presence of a spermiducal chamber. 



(5) Position of genital organs in A. stepJiensoni in segments 

 9 and 10. 



(6) Penial setal sacs provided with large massive glands as in 

 Tuhifex (Peloscolex) velutinus. The penial setge are also very long 

 like those of the above species, and very different from the ventral 

 setae. 



The antei-ior position of the genital organs in A. hasM, I think, 

 is a character only of specific rank not showing in any direct way a 

 closer relationship to the Naididee, for in some genera sucli as 

 Megascolex and Buchholzia f there are a few species in which the 

 genital organs are placed one or more segments in front of those, 

 which they generally occupy in the genus. In Tuhifex {Ilyo- 

 drilus) hecloti the genital organs lie in the 8th and 9th segments 

 and hence more anteriorly placed than in other members of the 

 family^ Among the Tubificidse Aulodr-ilus seems to have relations 

 on the one hand to genera Tuhifex, Ilyodrilus, and Psammorcytes, 

 and on the other to Branclihira and Kaioamuria. In possessing 

 hair setse, the long penial setse and the massive glands in 



* In A. limnobius, J. pleuriseta, and A. remex also the liearts lie in the 6th 

 segment. 



t In SuoJiholzia appendiculata Bucliholz, these organs lie in the 7th and 8th 

 segments, while in B. fallax Michaelsen , they occupy the usual position in the 

 familjf, i. e., in segments 11 and 12. 



