560 FRANK E. BEDDARD. 



exterior, as I have figured in Acanthodrilus (2, pi, xxx, 

 fig. 1), and as Prof. Spencer has figured in Megascolides 

 australis (9, pi. vi, fig. 21); but there is no branching 

 and anastomosis combined, such as is described above in 

 Libyodrilus; in Perichseta, &c., the network is confined to 

 the coelom, and is formed out of the proximal part of the 

 nephridia; in Libyodrilus the network is in the thickness of 

 the body- wall, and is formed out of the distal part of the 

 nephridia. It has been already explained that the paired 

 nephridia of the clitellar segments become rudimentary, 

 though they do not entirely disappear; if tlie coelomic part of 

 the nephridia were to disappear — and they have all but done 

 so in the clitellar region — the nephridial system would 

 consist merely of a rich network of smaller and larger 

 tubes in the thickness of the body-wall. 



The figure (fig. 14) which illustrates the arrangement of this 

 portion of the excretory system represents a combination of 

 several sections. It should be stated, however, that it is not 

 meant as a diagram ; such an arrangement as is there depicted 

 might well occur and be visible in the thickness of any one 

 section. To thoroughly demonstrate the network in the longitu- 

 dinal muscular layer probably needs some process of injection 

 which I have not been able to apply. Had I been aware of 

 this interesting network of fine tubes in the skin I should have 

 certainly attempted some injection while I had living speci- 

 mens at my disposal. As it is, I am inclined to think that I 

 have not in my drawing done full justice to the complexity of 

 the meshwork ; the scheme (fig. 16), which is purely diagram- 

 matical, expresses my idea as to this network. In fig. 14 two 

 longitudinal ducts (d) are shown, and the connection of each 

 with the circular vessel : the latter (c) is represented as cut at 

 diff'erent levels; the thickness of the walls of the tubes ramifying 

 among the longitudinal muscles is, perhaps, rather exag- 

 gerated. At a a branch of the longitudinal trunk d is seen 

 to leave the muscular layer, and to project into the body-cavity, 

 still surrounded by a connective-tissue sheath; this branch 

 joins one of the paired nephridia. 



