f 

 310 ><>rii '>;./.'//.- hi 'in Oligochafotu Ann>'/i<l. [Mav. .".. 



The system of tabes was everywhere accompanied by blood vessels ; 

 Imt, it is perhaps unnecessary to remark, there was nowhere any con- 

 nexion between these tubes and the capillaries ; no coagulated blood 



- in a single instance found in the excretory tubules. 



In spite of their very different appearance, as well as arrangement, 

 from the nephridia of other types, such as Pericliata, which possess a 

 diffuse nephridial system, the excretory nature of these tubes seems 

 probable, without any further description. A connexion with the 

 body cavity must be proved in order to remove all doubts as to their 

 nature; in each segment, just behind the pair of setae, the longitudinal 

 dtict gives off a branch, which passes through the peritoneum and 

 comes to lie in the coelom ; this branch continues for a short distance, 

 and then abruptly ceases ; whether it is furnished with an actual 

 orifice or not I am unable to say. In a few cases, the branch enter! 

 the ccelom became connected with a very small coiled nephridial 

 tubule, so small that it was not, as already mentioned, recognisable in 

 dissection. 



I am inclined to refer the atrophy of the intra-ccelomic part of t! 

 nephridia to their having been used up in the formation of t 

 genital ducts. I have recently communicated to this Society a noti 

 of the development of the genital ducts out of nephridia in Acantho- 

 drilus ;* and that mode of development is possibly general. In an; 

 case the nephridial system of the genital segments of this Eudrilid 

 swts almost entirely of a complex system of tubes, which ramify in 

 thickness of the body wall, which open by numerous pores on to thf 

 exterior, and are connected by a few short tubes with the body cavity. If 

 the tubes leading to the coelom became obliterated, and they are very 

 short as it is, the excretory system would consist only of the network 

 in the body walls. 



This system of tubes in the skin may perhaps be more comparable 

 to the nephridial network of Cestodes and other flat Worms, than the 

 intraccelomic network of other Oligochseta; its presence, however, in 

 the body walls suggests a comparison with the Nematoidea, which 

 appear to possess at least the remains of a coelom. In some of these 

 Worms a system of fine tubes connected with the excretory pore 

 permeates the interspaces between the longitudinal muscles. In 

 Echinorhynchus the tubes connected with the lemnisci also ramify in 

 the integument, and the lemnisci themselves are processes of the 

 body wall depending into the coelom. 



* ' Roy. Soc. Proc.,' vol. 48, 1891, p. 452. 



