ANATOMICAL STUDIES ON NEW SPECIES OF 

 OCNERODRILUS. 



BY GUSTAV EISEN. 



The genus Ocnerodrilus appears to be confined to the 

 American continent, where it has a large geographical 

 distribution, at least through the more temperate or trop- 

 ical regions. The expedition sent out by the California 

 Academy of Sciences to Baja California and Mexico 

 brought home quite a number of earth and water Oligo- 

 cha^ta, among others numerous specimens of at least two 

 new species of Ocnerodrilus, for which I here propose 

 the names of Ocnerodi'ilus Beddardi, and sonorcv. Other 

 species were found by me in Central America several 

 years ago. New specimens of Ocnerodrilus occidentalis 

 have also come to hand from the old and only locality 

 where it has been found to date, and I am able to add 

 some points to our previous knowledge of this worm. 

 Besides these species, another one has lately been de- 

 scribed by Beddard, from British Guiana, which in one 

 or two important points differs from those examined by 

 me. Thus there are known in all ten species of Ocnero- 

 drilus, all tropical or semi-tropical in their habits. The 

 systematic position of this genus is a most interesting one, 

 as showing affinities with both the water and with the 

 land Oligocheeta, with a closer relationship with the latter. 

 Among these the new genus- Gordiodrilus (Beddard) 

 shows the most affinities with our worms. The additional 

 species of Ocnerodrilus which I here describe will neces- 

 sitate a change in the genus characteristics as lately 

 formulated b}" Beddard, but will also further verify his 

 remark that both Ocnerodrilus and Gordiodrilus are 

 characterized principally by negative characters. 



2d Ser., Vol. III. January 19, 1893. 



