ANATOMICAL STRUCTURE OF KERRIA. 313 



According to Beddard the genital seta? in Kerria 

 Jialophila are similar to and thus not smaller than the 

 other setae. The difference in size of the setse is there- 

 for only a species characteristic, but one of considerable 

 importance as it is an exterior character which does not 

 require dissection to be descernible. 



Systematic -position. Beddard has already commented 

 upon the relationship of Kerria with other genera, and he 

 incHnes strongly to place it near Acanthodrilus, as well 

 as Ocnerodrilus and Gordiodrilus. I believe, however, 

 that the relationship with Ocnerodrilus, Gordiodrilus and 

 Pygmaiodrilus is greater and that those three genera with 

 Kerria may be arranged in one large group, though not 

 in the same family. The presence of blood vessels on 

 the nephridia appears in my opinion to further separate 

 Acanthodrilus from the other genera in question, and so 

 does undoubtedly the double row of cells of the prostates. 

 The size, shape and diverticula of the spermathecEe of 

 Kerria resemble more closely those of Acanthodrilus 

 than Ocnerodrilus, etc. But of all the genital organs the 

 spermathec^ are those which vary the most, even within 

 the limits of one species. 



