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OLIGOCHAETA 



assigned to the neighbourhood of the Lumbriculidae, but which are not of themselves 

 sufficient to show its affinities to that family more than to other families of the 

 aquatic Oligochaeta. 



The principal differences from the Lumbriculidae are the following: — 



(i) No vascular contractile caeca (these, however, are absent in Stylodrilus). 



(2) A single pair only of testes and sperm-ducts. 



(3) The position of the male-pores upon the thirteenth segment, and the 



related fact that the sperm-ducts pass through several segments on their 

 way to these pores. 



(4) The position of the ovaries in the thirteenth segment, and of the oviducal 



pores upon the following segment. 

 These characters do not unite this genus with the Tubificidae or with any other 

 aquatic Oligochaeta ; they point, on the whole, to the terrestrial genera, and 

 particularly, perhaps, to Allurus; hence the name Alluroides, which I have given 

 to the genus. I have already discussed these characters in the section dealing 

 with the general classification of the Oligochaeta. 



The affinities of this family in one direction are not plain ; the two pairs of sperm- 

 ducts, with the corresponding two pairs of testes, do not occur in any other group 

 among the aquatic Oligochaeta ; there is, so far, a resemblance to the terrestrial 



