1891.] Excretory Organs in an OUgoehcetou* Annelid. 309 



tications of the reproductive organs, and the present genus is no 

 exception to the rule in that particular ; but it shows a further 

 peculiarity in the structure of the nephridia ; the arrangement of 

 these organs in the clitellar region of the body is unique amon^ 

 Annelids, and is to a certain extent suggestive of the condition of the 

 organs supposed to be nephridia in certain Nematoidea. Throughout 

 the body generally, as in other Eudrilids, the nephridia are paired ; 

 in the genital region I was struck, on dissecting the worms, by the 

 apparent absence of nephridia. Sections through the body wall in 

 this region show that the longitudinal and transverse muscular layers 

 are traversed by a system of peculiar canals not at all like nephridia 

 in appearance. These canals are not mere clefts between the muscular 

 fibres, such as Kiikenthal has described in his paper " Ueber die 

 lymphoiden Zellen der Anneliden ;"* such lymph spaces I have found 

 a good many Oligochaeta, but they never possess a definite wall. On 

 ic contrary, the canals which I describe here have a definite darkly- 

 lining wall, with nuclei here and there. They resemble the blood 

 sssels very closely, and might easily be confounded with them. 

 These vessels are arranged in a longitudinal and a transverse series 

 tith numerous branches and interconnexions. The longitudinal 

 luscles are imbedded in a nearly homogeneous, transparent, connec- 

 ive tissue, which is of some thickness between the peritoneal 

 3ithelium and where the muscular fibres end. It is in the latter 

 3t of tissue that the four principal longitudinal trunks run. corre- 

 jnding in position to a line connecting the four successive pairs of 

 stae ; there appear to be smaller longitudinal trunks, but the four 

 icipal ones run through several segments without a break ; these 

 jgitudinal trunks are connected with a metamerically repeated 

 stem of transverse vessels ; these lie between the transverse and 

 )ngitudiiial muscular coats, and appear to run right round the body, 

 ley are of considerable calibre, but not so wide as the longitudinal 

 iks ; I could not detect any ciliation anywhere, and their walls 

 extremely thin. They give off numerous branches, which traverse 

 ie body wall in every direction, and form a finer meshwork of 

 ibules ; some of the branches run towards the epidermis, and 

 Ithough I could not detect in transverse sections the actual orifices, 

 account of the fineness of the tubes, I could make out at frequent 

 sints a slight modification of the epidermis which seemed to 

 arrespond to an external pore. 



Upon fragments of the chitinous cuticle being stripped off and 

 tamined with a high magnifying power, the orifices were quite plain, 

 ley were much smaller than the nephridiopores of Pericliceta, but 

 )t so minute as to be confounded with the pores of the gland cells 

 the epidermis. 



* ' Jenaische Zeitsclir. f. Naturw.,' vol. 18 (1885), p. 310. 



