DESCRIPTIONS OF GENERA AND SPECIES 573 



FAMILY EUDRILIDAE. 



DEFINITION. Oligochaeta of various size, with paired nephridia ; spermiducal 

 glands always present ; sperm-ducts open into these glands at some distance 

 from external orifice. Spermathecae (if present) impaired, and opening on to 

 exterior in the neighbourhood of female genital pores, generally replaced by 

 or, if present, enclosed in coelomic sacs, which are frequently connected with 

 the other parts of the female reproductive system. 



This family of earthworms is one which has only very recently become at all 

 known. It is undoubtedly, from many points of view, the most interesting family 

 of Oligochaeta, principally owing to the remarkable structure of the reproductive 

 organs. The family is, moreover, one which is distinguished by its geographical 

 distribution. With the sole exception of the type-genus, Evdrilus, the family is 

 restricted to the ' Ethiopian region,' being especially abundant in the equatorial 

 portion of the African continent. For a long time Eudrilus was the only genus 

 certainly known. More recently, ROSA, MICHAELSEN, and I myself have made known 

 a considerable number of different genera of Eudrilidae. 



Besides the genera and species referred to in the following pages, there is at least one of 

 the genera described by KINBERG that in all probability belongs to this family; this is Tritogenia. 

 It is thus defined by KINBERG (p. 98) : 



' Lobus cephalicus transversus, brevis, longitudinaliter striatus ; setae corporis anterioris dorsales 

 singulae, ventrales binae, corporis posterioris nullae ; tuberculum ventrale singulum.' 



The species Tritogenia sulcata is defined in these words : 



'Segmenta 80, plurima biannulata; tuberculum ventrale segmenta 17-19 praebens; longitudo 

 55 mm.' 



The species is from Port Natal, a likely locality for an Eudrilid. The chief reason which 

 leads me to regard the worm as an Eudrilid is, of course, the unpaired male pore and its extent ; 

 I think it possible that KINBERG had before him a species of the genus Polytoreutus, in which 

 there is an area of large extent before and behind the male pore ; but, the character is, indeed, 

 one which might suit a good many Eudrilids. The facts given by KINBERG are, it is hardly 

 necessary to state, not sufficient to fix the genus of the worm with any approach to correctness ; 

 it is not even absolutely certain that it is a member of the present family. It is said to have 

 only six setae ; this statement, if proved, would, of course, place it in a very isolated position ; 



it is possible that the outermost seta was overlooked by KINBERG. 

 I 



This group of worms contains species of all sizes ; at one end of the series are 

 such forms as Reithrodrilus minutus, which is barely two inches in length by one 

 millimetre in breadth ; at the other extremity we have the comparatively gigantic 

 Paradrilus rosae, a big worm measuring a foot and a half in length. 



