1914.] J- Stephenson : Oligochada from Northern India. 329 



The cerebral ganglion (text-fig. 4) is slightly bifid posterioily, 

 and has a concave anterior border. 



4 



Fig. 4. — Naidiion miuutum ; cerebral ganglion. 



Sexual organs were not present in any of the specimens. 

 Asexual reproduction was going on, and chains of two were usually 

 observed ; a chain of three, with two budding zones, was also seen 

 The budding zone establishes itself behind the twelfth segment 

 (n= 12) • and of the new segments formed m the zone, the hinder 

 seven, with a prostomium, are apportioned to the posterior 

 animal (text-fig. 5) ; in other words, in an animal which is about to 



r 



5. 



Fig. s. — A'aidiniH minntiim ; zone of budding. 

 py., prostomium. 



separate, the rudiments of six pairs of setal bundles are seen 

 forming in its anterior part. In such a specimen the prostommni 

 of the hinder individual may be seen projecting dorsalwards just 

 behind the line of approaching division (c/. text-fig.) ; although 

 after separation it is a small structure and not at all proboscis- 



Michaelsen (5) has recently united the genera Naidium and 

 Pristina under the latter name; though Piguet (9) still more 

 recently prefers to retain them as separate. Without claiming to 

 decide the point, and reserving judgment till the genital organs ot 

 Naidium have been described, it may be noted that an indication 

 of the close relationship between the two is furnished by the 

 facts of asexual reproduction. In Pristina, as I have P^^eviously 

 stated (12), the number of segments at the anterior end which 

 have been produced in the budding zone is seven,— i.e. six seta- 

 bearing segments, a first segment without setae, and a prostomium. 

 This is exceptional in the Naididae ; the number of such segments is 

 in the majority of cases five, or two less than in Pristma ; and it is 

 interesting now to find that in a species of Naidium (on which 



