1897.] rno.M SOUTH aprica. 347 



coloration produced by the blood-vessels. The skin is thin and 

 several of the organs show plainly through. As in nearly all 

 Eudrilidae, dorsal pores appear to be completely absent. The only 

 exception seems to be the genera Plutydrihis and Eudriloides. 

 In no other family of terrestrial Oligochaeta is there this nearly 

 complete absence of structures so characteristic of earthworms. 

 The absence of these pores may perhaps be related to the pai'tially 

 aquatic life of at any rate many members of the family ; on the 

 east coast of Africa the species of Eiidrilidas are largely met with 

 in swamps, and we know that the purelj^ aquatic genera of Oli- 

 gochseta are without the dorsal pores for the most part. Exceptions 

 to the statement occur among the aquatic members of the genus 

 Acanthodrilus. But among the " Limicolae " of Claparede there 

 are no exceptions. Another feature in the organization of the 

 Eudrilidae which may possibly be correlated with the absence of 

 dorsal pores, is the often exceedingly dark pigmentation of the 

 chloragogen cells which cover the intestine, and the accumulations 

 of secretory products within the peritoneal cells which cover the 

 nephridia. If the dorsal pores have an excretory function, their 

 absence would naturally lead to a greater accumulation of such 

 waste substances as those referred to. That many of the Eudrilidae 

 have a great deal of pigment in the skin may be another fact to be 

 noted in the same connection. But this pigmentation is not more 

 excessive than in worms which possess doi'sal pores. 



The setce have the arrangement that characterizes others of the 

 West African genera that have been mentioned as nearest of kin. 

 The ventral setae are at some distance from each other, while the 

 more dorsally placed pair are strictly paired. The distance which 

 separates the two setae of each ventral pair is five or six times as 

 great as that which intervenes between the two setae of the dorsal 

 pair. The setae themselves present nothing noteworthy in their 

 form ; they are rather small and not obvious until the skin is 

 examined with the microscope. 



The nepliridiopores are very conspicuous orifices lying in line 

 with the dorsal pair of setae. 



When a piece of the skiti is examined after being well cleared 

 with glycerine the tegumentary sense-bodiea, which occur in many 

 Eudrilids, are to be seen. These structures, which have so curious 

 a resemblance to the Pacinian corpuscles of vertebrates, lie im- 

 bedded in the skin here and there apparently without regular 

 arrangement. They are in the present wonn of an elongated 

 from and lie invariably with their long axis corresponding with 

 the long axis of the worm's body. 



The clitellum, as in many other species, is developed right round 

 the body, having therefore the form to which it has been proposed 

 to restrict the term cingulum. It occupies segments xiii.- 

 xviii. 



The generative orifices are exceedingly conspicuous. They are 

 unpaired. 



The female orifice is situated on the boundary line of segments 



23* 



