DESCRIPTIONS OF GENERA AND SPECIES 



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I shall now consider a group of Cryptodrilidae which have been referred to 

 four distinct genera, and which should, as I think, be included in one group ; 

 I refer to Ocnerodrilus (including Pygmaeodrilus), Nannodrilus, and Gordiodrilus. 

 These genera agree with each other, and differ from most earthworms (I shall mention 

 an exception presently) in the following characters : 



(1) The calciferous glands, paired or single, lie in the ninth segment. 



(2) The spermiducal glands are lined by a single layer of cells only. 

 Besides these points of resemblance, there are other agreements in various 



characters, which, though not unknown in other worms, mean something, perhaps, 

 collectively. Such are : 



Absence of penial setae ; small size ; commencement of intestine in twelfth or 

 fourteenth segment ; absence of typhlosole ; paired nephridia ; last pair of hearts 

 in eleventh segment ; setae strictly paired. 



Even if we take the most characteristic form, and one only of each of these 

 genera, it is difficult to show contrasts that would be regarded as sufficiently marked 

 to permit of so wide a separation as EISEN (1, 4) would institute, except perhaps in 

 the case of Gordiodrilus tenuis, of which more presently. 



For instance, let us compare Gordiodrilus elegans, Ocnerodrilus eiseni, and 

 Nannodrilus africanus. 



Slender though these differences are, yet they must be held to be of sufficient 

 importance to allow of generic separation. Too much stress cannot be laid upon 

 the presence or absence of diverticula to the spermathecae. Although, among 

 earthworms, diverticula are very constantly either present or absent in a family, 

 let alone a genus, there are several instances where a genus has or has not, according 

 to the species, diverticula appended to the spermathecae. But, nevertheless, we cannot 

 but allow that G. matthewsi and G. elegans belong to the same genus, though one 

 (G. elegans) has not, and the other has, at least traces of a pair of diverticula appended 



