114 



Records of the Indian Museum. 



[Vol. Ill, 



modified (genital sete), the prongs of the distal end being much 

 shorter, and the nodulus more distinct (v. text- 

 fig. 3)- 



Of the three genera of Tubificidse which pos- 

 sess only forked setee in the dorsal as well as in 

 the ventral bundles, — Limnodrilus, Clitellio and 

 Vermiculus, — ^he two latter are immediately 

 excluded by the characters of their genital appara- 

 tus, since Vermiculus possesses single male and 

 spermathecal pores, and Clitellio has no prostate. 

 It seems probable that the present form is a 

 Limnodrilus and that the differences from the usual 

 descriptions of that genus are, in part at least, 

 due to the fact that the examination has been 

 made on preserved material. A few points may, 

 however, be further mentioned. 



One would not expect the integumental blood- 

 vessels, which form one of the characteristics of 

 Limnodrilus, to be recognizable in preserved 

 specimens ; but I am a little surprised that the 

 " hearts " of segment viii, or viii and ix, give 

 so little evidence of ,their existence ; they are 

 immediately visible, for example, in preparations 

 of a small Limnodrilus from Lahore (species un- 

 determined, as I have not yet met with mature 

 specimens) , in which also the main vessels can be 

 followed with ease ; this is by no means the case with the Tibet 

 s])ecimens. It is to be rememl)ered, however, that the " hearts " 

 need not be specially enlarged vessels ; their contractility is their 

 special characteristic. 



The vas deferens, again, is in Limnodrilus distinguished by its 

 great length, and by being narrow and much coiled (Beddard, 

 OligochcBta, p. 249). This cannot be said of the present form, in 

 which it is comparatively shoit and stout, and is not coiled : and 

 this difference does not seem to be due to the fact of the animals 

 being examined in the preserved state. 



I have not been able to observe the character of the spermato- 

 phores mentioned by Beddard, namely that the free ends of the 

 spermatozoa form a spiral on the outer surface. 



Admitting, however, this form to a place in the genus Limno- 

 drilus, the species must, I fear, remain undetermined ; the dis- 

 crimination of the various species depends largely on the 

 characters of the penis and its sheath, and to some extent also 

 on the shape of the brain, — organs of which unfortunately I can 

 only give incomplete descriptions. I may refer to Beddard 's 

 words (p. 251, op. cit.), referring to the occurrence of the genus in 

 Hawaii : "I cannot distinguish an}- marked peculiarities which 

 justify me in giving it a new name, though on the other hand I 

 have not yet identified it with any of the known forms. Living 

 material is essential for the proper description of these Tubificids." 



Pig. 3. — Genital 

 setae of Litmwdri- 

 lus sp. (?) ; by the 

 side of the fully- 

 formed seta is a 

 young one in pro- 

 cess of formation : 

 compare with text- 

 fig. 2. 



