Zoolorjical Notes. 103 



finger-like processes attached to both sides of the sej)tum. 

 These bunches are paired, and lie close on either side of the 

 nerve cord. I gather from ClaparMe's description that in the 

 species studied by him the paired arrangement of the testes 

 was not apparent; it was so, however, in the examples 

 studied by myself. I am, so far, in accord with Michaelsen, 

 wlio, taking P. germanicus as a type of those Pachydrili 

 which live on the shores, and in all of whicli the testes are 

 lobate, states that the testes are paired and lie in the 11th 

 segment. But I understand Michaelsen to imply that in 

 P. maximtis, P. nervosus, and P. gerynanicus there is only a 

 single pair of testes ; my species therefore agrees rather with 

 Claparede's P. verrucosiis, and it seems to me to be possible 

 that Claparede was in error in stating that the testes form a 

 single mass attached only at one point to the septum. The 

 observations of Claparede and Vejdovsky just referred to seem 

 to imply that there are two pairs of testes, but in his latest 

 work upon the subject Vejdovsky (4, p. 132) places the testes 

 oi Pachydrilus in segment 11 in a table indicating the posi- 

 tion of the reproductive organs of the principal genera of 

 Oligochseta. I have studied, by means of longitudinal 

 sections, four individuals of a species which I believe 

 to be identical with P. verrucosus, and in all of these 

 there were distinctly two pairs of testes attached to the 

 anterior and posterior surface of the septum dividing seg- 

 ments 10 and 11. Of P. nervosus I have studied two speci- 

 mens ; in one (which was immature), there were two pairs 

 of testes occupying an identical position with those of P. 

 verrucostts, in the other specimen I could only find one pair 

 attached to the anterior septum of segment 11. It appears, 

 therefore, that there may be some individual variation in the 

 number of testes. In P. verrucosus the testes were larsjer in 

 the immature individuals, where they form bunches of long 

 processes as figured by Claparede and Vejdovsky; in the 

 single fully mature specimen the testes were short, thick, 

 Ipbed organs ; this difference is probably due to the fact that 

 in the latter the gi-eater part of the testicular cells had been 

 converted into spermatozoa, and the organs themselves were 

 in consequence decreased in size. 



