:>G4 MR FRANK E. BEDDARD ON THE ANATOMY OF OCNERODRILUS. 



Tin.' genus has l)ecii recently met with by Eisen in Central America, but at present 

 there are no particulars as to the structure of the four new species, which he briefly 

 mentions as having been found by himself [2, p. 5, footnote]. 



Ocnerodrilus, therefore, has probably a wide range over the warmer parts of the 

 American continent, and is, so far as we know at present, confined to that continent. 



I. Structuke of Ocnerodrilus. 



§ External Characters. 



Figure 5 shows an individual of the natural size after preservation in corrosive 

 sublimate, followed by alcohol. Fig. 2 illustrates some of the principal external 

 characteristics. 



The prostomium is present, but not in any way specially remarkable. 



The setce are strictly paired, and are of the usual shape that is met with in Earth- 

 worms. There is no modification of the clitellar setae, except that the ventral pair of 

 segment XVII in fully mature individuals are totally wanting. 



Dorsal pores are aboent. 



The clitellum includes segments XIII-XVIII; it commences and terminates abruptly. 



The nephridiopores open in front of and a little to the outside of, the ventral pair 

 of setae ; there are a pair to each segment, commencing with the third. 



The spermathecal pores lie between segments VII and VIII, on a line with the 

 ventral setae. 



The oviducal pores are upon the XI Vth segment, in front of the ventral pairs of setae. 

 The male pores occupy a corresponding position upon the XVIIth segment, though the 

 setae are absent. 



Judged by external characters only, Ocnerodrilus would be referred to the Crypto- 

 drilidae among Earthworms. We shall see that its internal anatomy shows many resem- 

 blances to that family. 



§ Body Wall. 



Eisen gives no account of the histology of the body wall in Ocnerodrilus, referring 

 only to the characters of the setae, which are figured [1, pi. i. fig. 2). Nor is the clitellum 

 described. This organ is of great importance in determining the affinities of the different 

 genera of Oligochaeta. particularly in some families. Had the clitellum been developed 

 in any of the specimens examined by Eisen, he would hardly have referred the genus to 

 the family Lumbriculidae. 



A considerable proportion of my examples were furnished with a fully developed 

 clitellum ; but there were others, fully mature as regards the sexual organs themselves, in 

 which there was no trace of a clitellum. Eisen states that his species is mature in the 



