125 



Beddard ('95, p. 314) and Michaelsen ('00, p. 88) classed it among 

 the Enchytrccidcc. Later, Michaelsen ('03b, p. 50) included it with the 

 Tuhificid(€. As there seems to be good ground for putting it with 

 the Tiibificidcr it has been omitted from the above list. 



The abundance of enchytrseid life in North America is indicated 

 by the fact that in spite of the small amount of investigation w^hich 

 has been made in this group, nine of the above-listed genera are known 

 to have representatives on this continent, and it seems safe to predict 

 that future investigation will reveal still other genera. An indication 

 of what further studies may yield is afforded b}' the work of Eisen 

 on the Pacific coast, where random collecting gave material from 

 which he described forty-eight new species distributed among eight 

 genera; and in his introduction he states that he had at the time of 

 wTiting some fifty or more additional new species from the same 

 region, the description of which was temporarily prevented by un- 

 avoidable circumstances. 



Of the above-listed genera only Distichnpns, which was described 

 by Leidy in 1882 from the eastern United States, is, so far as our 

 knowledge goes, limited to North America. The following genera are 

 represented in this country : McscncJiytrcciis, Bnchytrcriis, Michael- 

 sena, LnuibriciUits, Marionina, Bryodrilus, Hcnlea, Fridericia, and 

 Distichopiis. 



Key to the; Genera oe North American ENCHvTRiEm.T: 



1 (2) Setae not disposed in bundles; occur singly when present; usu- 



ally absent from many of the somites MichaeJsena 



2 (i) Setae disposed in bundles. 



3 (4) Setae disposed in two bundles on each somite Distichopiis 



4 (3) Setae disposed in four bundles on each somite. 



5 (6) Dorsal pores present Fridericia 



6 (5) Dorsal pores absent. 



7 (8) CEsophagus merges suddenly into the intestine Henlea 



8 (7) CEsophagus merges gradually into the intestine. 



9 (10) Setae straight and of equal length Enchytrams 



10 (9) Setae sigmoid. 



11 (12) Testes plurilobed Lumhricilhis 



12 (11) Testes undivided. 



13 (14) Origin of dorsal vessel intraclitellar ; blind diverticula in con- 



nection with alimentary tract somewhere in VI— VIII 



Bryodrilus 



14 (13) Origin of dorsal vessel postclitellar ; no diverticula in connec- 



tion with anterior part of alimentary canal. 



