120 OLIGOCHAETA 



already attempted to show that the spermiducal glands in the Geoscolicidae are like those 

 of the Eudrilidae more than any other group. In Microcheta benhami, also, there are a 

 series of quite analogous glands which are referred by KosA to the same category as the 

 spermiducal gland ; he also holds this view with respect to the posterior glands of 

 Pontoscolex, Urobenus, and Brachydrilus ; as regards this latter comparison I may point 

 out that the connexion of the glands of Pontoscolex- with the nephridia is curiously 

 paralleled by the connexion of the spermiducal gland of ffeliodrilus with the nephridia 

 of its segment ; this connexion, however, may not be more than accidental in the latter 

 case. The existence of this relation, especially in Pontoscolex, suggests that perhaps 

 Rosa has not gone quite far enough back in seeking for the origin of the glands. 

 It may be that the glands, with which I think with Rosa that the spermiducal glands 

 are homologous, are themselves derived from the nephridia ; as we now know that the 

 sperm-ducts are homologous with nephridia, the connexion of the sperm-ducts with 

 the spermiducal glands may be in this case comparable to the connexion of the nephridia 

 of Pontoscolex with the posterior glands ; this, however, does away with the significance 

 of the connexion between the two in Heliodrilus. The glands in Kynotus lying behind 

 the spermiducal glands are provided with modified setae, and thus the resemblance 

 to the spermiducal glands, as they usually are, is completed; we must not, perhaps, 

 leave out of consideration the anteriorly situated glands, also provided with modified 

 setae in a few species of Acanthodrilus (s. 1.), &c. ; these are very likely to be placed 

 in the same category. It is possible that the glands which are so often found in the 

 neighbourhood of the male pores and the spermathecal pores in the Perichaetidae 

 should be also referred to the same series ; but it may be remembered that these 

 latter have no lumen, and would therefore, have to be looked upon as much 

 degenerated. StiU their frequently paired arrangement, corresponding to that of 

 spermiducal glands, is an argument to be borne in mind. The spermatheeae also 

 suggest the same origin, but I deal with their homologies under the heading 

 ' Spermatheeae ' (see below). 



Closely connected with the last question, and, of course, with the phylogeny 

 of the Oligochaeta, is another question: what is the most primitive form of the 

 spermiducal gland? If we accept their serial homology with the. copulatory glands 

 it is evident that those spermiducal glands which are structurally most like the 

 copulatory glands will have to stand at the base of the series. It should be noted 

 in the first place that there seems to be a certain relation between the copulatory 

 glands and the spermiducal glands in those few forms in which they coexist ; that is 

 to say, differences in the structure of the copulatory glands are repeated in the 

 spermiducal glands. In Kynotus both glands have a muscular covering; in 



