242 J. T. CUNNINGHAM. 



only connected with the phenomena of reproduction as efferent 

 ducts. There are five pairs placed in the fourth to the eighth 

 setigerous segments. Three parts are distinguishable in each 

 organ, the funnel, the gland, and the vascular reservoir. He 

 describes correctly the fringed and ciliated dorsal edge of the 

 funnel ; but his account of the shape of the glandular part, 

 which he compares to a comma, does not agree perfectly with 

 what is seen in A. marina. His figures are not good, though 

 creditable for the date at which they were made. Claparede 

 never saw ova in the interior of the nephridia, but once saw 

 spermatozoa in the funnel. Of Arenicola marina, Lin., he 

 says merely that the segmental organs have a great analogy 

 with those of A. Grubii. 



Casmovici's description of the nephridia and gonads in 

 Areniola marina is correct in almost every particular; his 

 figures of minute structure are not satisfactory, but his ana- 

 tomical figures are clear and accurate ; and if it were not for 

 the absurd manner in which he has separated the nephrosto- 

 mata as distinct organs from the nephridia themselves, his de- 

 scription would be worthy of a permanent place in zoological 

 literature. To him, in any case, is due the credit of having 

 been the first to discover and describe the true gonads in 

 Arenicola. He states there are six pairs of nephridia, each 

 with its external opening, and situated in the third to eighth 

 somites. The external opening of each organ is situated close 

 behind the upper end of the corresponding uncinigerous torus. 

 The funnel or nephrostome is correctly described by Cosmovici ; 

 it is provided with a free membranous dorsal border, fringed 

 and ciliated. Along this border runs a pseudhsemal vessel, a 

 branch from the branchial artery, which is given off by the 

 ventral vessel. (Cosmovici believes the ventral vessel to be con- 

 nected with the heart, and to be arterial ; it is more probably 

 venous ; that is, it probably receives the blood from the 

 branchise.) The vessel which runs along the dorsal border of 

 the nephrostome is continued diagonally backwards and out- 

 wards across the nephridium, and in this part of its course, 

 posterior to the nephrostome, it runs through the gonad ; the 



