DESCRIPTIONS OF GENERA AND SPECIES 



637 



in the retracted condition (see ac- 

 companying woodcut) as a rounded 

 process nearly blocking up the 

 mouth. This accords with VAIL- 

 LANT'S observations rather than with 

 those of PERKIER ; the reader is also 

 referred to the description of Tricho- 

 chaeta (below), where a proboscis of 

 a similar character exists. 



The clitellum (see woodcut, fig. 51) 

 is, as in other Geoscolicidae, saddle- 

 shaped ; anteriorly the ventral area 

 upon which there has been no de- 

 velopment of glandular tissue, is 

 narrower than it is posteriorly ; the 

 number of segments occupied by the 

 clitellum is ten or eleven, com- 

 mencing with the fourteenth ; in 

 R. tenkatei and R. parudoxus there 

 is some doubt as to the limits of 

 the clitellum. As in Pontoscolex 

 and other genera the clitellar setae 

 are usually longer, straighter, and 

 more distinctly sculptured than the 

 setae of other parts of the body; in 

 R. ecuadoriensis alone there appear 

 to be no differences between the 

 setae of the clitellum and those 

 which occur elsewhere. In R. tenkatei 

 there are bundles of four setae re- 

 placing the ventral pairs of setae 

 of the seventeenth, eighteenth, and 

 nineteenth segments. These in all pro- 

 bability correspond to the copulatory 

 setae (and glands) found in certain 

 species of Microchaeta, Tykonus, and 

 in Kynotus. 



Fig. 5i- 



Fig. 52- 



RHINODRILUS GULIELMI. 

 ANTERIOR SEGMENTS OP 

 BODY. 



RHINODRILUS GULIELMI. 

 NAT. SIZE. 



