228 Proceedings of the Royal Society of Victoria. 



Each gives off a series of vessels supplying the nephi-idia 

 (Fig. 20). These at first retain their muscular character, but on 

 ramifying through the organs their muscularity becomes gradu- 

 ally less marked (Fig. 21 Bv. 2) and finally disappears entirely. 

 The capillaries are distributed through the botryoidal tissue and 

 from these branches arise which enter the sinuses. 



Nephridia (Figs. D., 20 and 21). 



There are seventeen pairs of nephridia, one pair being situated 

 in each of the segments VI. -XXII. 



The nephridium may be divided into three parts for the 

 purpose of description : — 



1. The internal, connected with the coelom. 



2. The central, making up the greater portion of the organ. 



3. The part connected with the exterior. 



The internal part connected with the coelom may be called, as 

 in other cases, the testicular lobe, but its structure is different 

 from that of Hirudo. It is intracellular but unbranched, and 

 lies latero-ventrally near the outer margin of the testis. The 

 extreme end of the lobe may be called the funnel (Fig. D., fun.) 

 Owing to the coelom being much reduced there is less work 

 thrown on this part of the organ and it is consequently somewhat 

 modified. Like Hirudo it consists of a group of nucleated cells 

 which may be described as a cauliflower head being thrown into 

 folds. It is, however, much smaller in comparison than that in 

 Hirudo. There is no definite opening from the funnel into the 

 coelom. In this respect it resembles Ijoth Hirudo and Aulosto- 

 nium according to the descriptions given by Bourne and by Graf.^ 

 As far as I can make out the cells are not ciliated, so that this 

 point and the relation of the funnels to the sinuses show distinct 

 differences as compared with Hirudo and Aulostomura. In 

 Hirudo, Bourne says the funnels lie in a special blood sinus — 

 tlie perinephrostomial sinus — surrounded by blood and, in those 

 segments containing testes, situated on the dorsal wall of the 

 testes. 



In Aulostomum, Graf found that the funnels lie in sinuous 

 vesicles dorsal from the testis and at the side of the intestine. 



1 Q.J.M.S., July, 1884 ; Trans. New York Acad. Sc, xiii., 1894. 



