AN ATTEMPT TO CLASSIFY EARTHWORMS. 263 



Species 1. A. tetraedrus, Sav., 1832; Europe. 

 See Beddard, ' Quart. Journ. Micr. Sci./ xxviii. 



Remarks on Lumbricidse. 



Eisen was the first to subdivide the genus Lumbricus into 

 two sub-genera, according to the relative amount of dovetailing 

 of the prostomium into the peristomium. This is accompanied 

 by certain other characters, which have been held sufficient to 

 characterise genera in other cases. So that I retain his sub- 

 divisions Lumbricus and Allolobophora ; but as his genus 

 Dendrobsena is only distinguished from the latter genus in 

 having all the setse equidistant, and as all stages occurring in 

 this separation are found in Allolobophora, I agree with 

 Rosa that we ought not to recognise it. 



The anatomy of Criodrilus, recently worked out by Rosa 

 and myself, and again by Collin, is not very greatly different 

 from that of Allolobophora. The most important points of 

 difference are in the extent of the clitellum — which, till my dis- 

 covery of it, had been denied, and in which Collin confirms 

 me — and in the fact that this glandular modification of the epi- 

 dermis commences in Somite xv ; together with the absence of 

 spermathecse. This last character — which at first sight seems 

 to mark it off from the rest of the family — serves in reality as 

 a further link; for spermathecae are absent in Lumbricus 

 eiseni, Levinsen,^ and in Allolobophora constricta, 

 Rosa.^ This negative character is, as Rosa has recently ^ 

 pointed out, accompanied by another negative character, viz. 

 the absence of tubercula pubertatis — structures almost 

 limited to the family Lumbricidse, as they have only been 

 mentioned or figured in the species of Rhino drilus, and in 

 Hormogaster. 



The spermatophores, so noticeable a feature in nearly 

 every adult specimen of Criodrilus, are also known in many 



^ Levinsen, ' Syst. geogr. oversigt over de nordiske annulata,' &c., Copen- 

 hagen, 1883. 

 ^ Rosa, ' II Lumbricidi del Piemonte,' 1884. 

 2 Rosa, ' Boll, Mas. Zool. ed Anat. Comp.,' Torino, vol. iv, November, 1889. 



