38 EARTHWORMS AND THEIR ALLIES [ch. 



Benham that my genus Hesperodrilus is to be merged 

 in Phreodrilus, in Patagonia also. 



In this genus the male pores are upon the xuth 

 segment while the spermaries lie in segment xi. 

 Moreover the spermathecae lie behind the male 

 pores. In the Tubificidae on the other hand it is 

 at least the rule for the spermaries and male pores 

 to be pushed a segment further forwards. And the 

 spermathecae are before the male pores. Phreo- 

 driloides is like Phreodrilus but has no spermathecae. 

 It is also New Zealand in range. Astacopsidrilus is 

 Australian and is semi-parasitic upon the Crayfish 

 Astacopsis, whence its generic name. Phreodrilus 

 branchiatus is one of the few forms of Oligochaeta 

 that possesses gills. Of these there are a series of 

 pairs on about the last eleven segments of the body. 

 They are lateral in position, and thus contrast with 

 the also gilled Bramhiura sowerbii, where the gills, 

 also on the posterior segments of the body, are more 

 numerous and lie dorsally and ventrally, a pair to 

 each segment. 



The Tubificidae differ from the Phreodrilidae 

 mainly in the points already noted. There are a 

 considerable number of genera of which the following 

 are the best known, viz., Tubifex, Ldmnodrilus, 

 Limnodriloides, Branchiura, Lophochaeta, Ilyo- 

 drilus, Psammoryetes, Clitellio, Telmatodrilus, 

 Bothrioneuron, Lycodrilus. 



