AND ZOOGEOGRAPHY OF INDIAN OLIGOCH.V.TA. 109 



of the countiy. Trigaster is not known outside Mexico and the 

 West Indies. Deriving Ettdichog aster from Octocluetus, we need 

 no such hypothesis as that advanced by Michaelsen— the origin 

 of EucUchogaster from Trigaster in America, and its spread by 

 means of land-bridges across the Atlantic and Indian Oceans (or 

 alternatively the spread of Trigaster itself by the same means) as 

 far as India. EucUchogaster would have arisen where we find 

 it — in India, where its ancestor also lives. 



■I conclude, therefore, that Eudichog aster ai-o^e from Octocluptus 

 in India. It must therefore go into the Octochjetmaj, not the 

 Trigastrinse. 



Ramiella, gen. nov. 



I propose now to consider the more primitive species of the 

 genus Odochcetus to which reference has been made in the pre- 

 ceding paragraphs. 



In 1914 (7) I described a worm which I placed in the genus 

 Octocluetus under the name 0. bishamhari, although it differed 

 from all species of Octocluetus then known in having no calciferous 

 glands, and in having only one nepliridium on each side in each 

 segment. Measured by its size, indeed, this nephridium woidd 

 be a meganephridium, and the worm would not be an 



Octochcetus at all, but an Acanthodiiline — a " JS'otiodrilus " and 



would correspond to the original Acanthodriline, the origin of 

 the Megascolecidte, This, however, seemed impossible; there are 

 no representatives of the Acanthodrilinse in India (except one 

 introduced species of Microscolex) ; and the single nephridium 

 does not, according to the evidence of sections, come into relation 

 with the septum in the normal \A'ay, and is therefore to be looked 

 on as a hypertropliied micronephridium, the only one left of a 

 former larger series. 



In 1920 (11) two more forms closely related to the preceding 

 came to light. While both, Octochcetus 2)achpaharensis and 0. 

 2)allichis, are without calciferous glands, the first has onh^ three 

 (or anteriorly perhaps fewer) micronephridia on each side per 

 segment, and the second only about seven. 



This reduction in the number of micronephridia is probably 

 — certainly in the case of 0. hishamhciri — to be looked on as 

 secondary, while the absence of calciferous glands is probably 

 primitive. Other primitive features are the presence of all the 

 septa in the anterior part of the body (behind the level at which 

 they first definitely begin), and the absence of spines or teeth 

 on the penial setae. 



It is apparently from this group that EucUchogaster has arisen, 

 as I have argued above. Since the group is a well-defined one, 

 is. differentiated from the remaining species of Octochcetus by 

 morphological characters of importance — absence of calciferous 

 glands, reduction in the number of micronephridia — and has 

 different relationships from those other species, I pi-opose to 

 erect for them a new genus, BrnnieUa, which I associate with 



