I] STRUCTURAL AND SYSTEMATIC 41 



worms. The spermatliecae open close to the median 

 dorsal line of the body in one species; in A. tangan- 

 yikae there is but one spermatheca which opens 

 actually in the dorsal median line between segments 

 VIII and IX. This family seems to come nearest to the 

 Lumbriculidae but has also obvious points of likeness 

 to the terrestrial Moniligastridae. It fully deserves 

 a separate family, which was founded for it by 

 Dr IVIichaelsen. 



Not obviously related to any of the other families 

 of Oligochaeta is the family Enchytraeidae. This 

 consists of a very large number of species, which are 

 placed in about a dozen genera, and whose habitat 

 is nearly confined to the cold and temperate regions 

 of the world. A large number of species for example 

 have been described by Dr Eisen from Alaska, while 

 others inhabit the verge of Patagonia. It is only a 

 few which are found in warmer countries. There is 

 for instance a solitary Enchytraeid in India and the 

 neighbouring parts of Asia described by myself as 

 Henlea lefroyi but doubtfully of that genus according 

 to Dr Michaelsen. I have also myself obtained 

 another Enchytraeid from British Guiana. Apart 

 from such rare exceptions the family is arctic or 

 temperate in its range and is even met with upon 

 the ice of glaciers. These little worms they are 

 very rarely of more than minute size are both 

 aquatic and terrestrial and inhabitants of the sea 



