1892,] SPECIES OF EARTHWORMS. 679 



The differences between the two forms may be stated in a tabular 

 form as follows : — 



SetcE. — In A. georgianus the distance separating the two setse of the 

 lateral couple is hardly greater than that which separates 

 the ventral couple. 

 In my species, which I propose to call A. faldandicus, the 

 distance between the lateral setse is markedly greater than 

 that between the ventral setae. 

 Nephridiopores, — In A. georgianus these are placed in front of and 

 below the third seta. 

 In A. faldandicus these pores are directly in 

 front of the third seta of each segment. 

 Gizzard, — Totally absent in A. georgianus. 

 Rudimentary in A. faldandicus. 

 Penial setce. — In A. georgianus these have fewer tubercles upon the 

 extremity and these tubercles have no serrations. 



Michaelsen goes on to suggest that my species is possibly identical 

 with Rosa's Acanthodrilus bovei. I am not able, however, to adopt 

 this suggestion^ and for the following reasons. 



In the first place Acanthodrilus bovei is a much smaller species 

 than the one named by myself Acanthodrilus faldandicus ; the 

 measurements of A. bovei are 35 mm. in length by 3 mm, in 

 diameter ; A. faldandicus measures 60 mm. in length and upwards. 



Of A. bovei the prostomium is said by Rosa to extend on to the 

 buccal segment for about two-thirds of the length of the latter ; the 

 prostomium is less extensive in A. faldandicus. 



Tlie clitellum in A. faldandicus is quite complete, extending 

 right I'ound the body ; in the species with which it is sought to 

 identify my A. faldandicus there is a non-glandular triangular area 

 reaching as far forwards as the xvth segment, 



Acanthodrilus faldandicus possesses a pair of papillae upon the 

 xth segment which lie behind the ventral setae — exactly behind 

 them. In A. georgianus Michaelsen has described a similar pair of 

 papillee upon the tenth segment, but not anything is stated with 

 regard to their position upon the segment except that they lie upon 

 the seta-line 2. In A. bovei there are such papillae, but they lie 

 between the ventral setae on segments x. and xi. ; Rosa also speaks 

 of an oval area occupying a median position upon the ninth segment. 



These differences are, I think, sufficient to distinguish my species 

 from HosR'fi Acanthodrilus bovei^, though doubtless the two are very 

 nearly related. In my paper upon the anatomy of this form I 

 referred to its occurrence in fresh water as well as upon the land ; I 

 have since re-examined more carefully the specimens which occurred 

 in water, and I find that they are really different from A. faldandicus, 

 though very nearly related ; indeed the differences between all of 

 these Patagonian Acanthodrilidae are not very large. 



^ " I Lombrichi clella spedizione antarctica italiana del 1882," Ann. Mus. 

 Oiv. Geneva, ser. 2 a, vol. vii. p. 143, 



