I] STRUCTURAL AND SYSTEMATIC 39 



The Tubificidae are mainly northern temperate 

 forms, and a few of them such as CUtellio arenarius 

 and ' Pelorijctes i7iquilina^' are found on the sea 

 coast. There are also a few of this family in the 

 southern hemisphere. These forms include CUtellio 

 abjornseni from Australia, and a few species of 

 Branchiura from New Zealand and the islands of 

 the Antarctic ocean. There is also to be mentioned 

 Rhkodrilus (or Vermicidiis) aucMandicus from the 

 island of that name in the New Zealand area. The 

 only tropical species appears to be the Indian and 

 Malayan Bothrioneuron iris, though this genus also 

 occurs in Europe and in southern South America. 

 It is quite likely however that Branchiura sowerbii, 

 a species known at present from tanks in hot houses, 

 may be a tropical American species. 



The family Lumbriculidae is yet more restricted 

 in its range. It has not yet been met with away from 

 the temperate northern hemisphere, and the great 

 variety of species recently described from Lake Baikal 

 by Dr Michaelsen is a very remarkable fact. The 

 Lumbriculidae are entirely fresh water in habit and 

 not even partially terrestrial. The following are the 

 principal known genera : I/umhriculus, Trichodrilus, 

 Rhyachehnis, Phreatothrix, Clapaixdilla, Stylo- 

 drilus, Mesoporodrihis, Sidroa, Eclipidrilns, Auran- 

 tina, Athecospermia, Lamprodriliis, Teleidoscolex. 



1 With many synonyms, including TubiJ'ex ater (see p. 53). 



