1887.] ANATOMY OF EARTHWORMS. 3^7 



Like E. peregrinus, the present species is a native of the continent of 

 South America; in both the clitellum occupies segments 14-18 

 inclusive. M. Perrier describes in tlie 10th segment, " une sorte de 

 toute petite masse glaudulaire, absolument indeterminable," which 

 may possibly be one of the median ventral oesophageal glands already 

 described (p. 375). 



II. Further Note on the Reproductive Organs of 

 Acanthodrilus. 



In the 'Proceedings' of this Society for 1885 I published an 

 account of the anatomy of three species of the genus Acanthodrilus. 

 On reexaiuiuing my preparations, I find that 1 have misintei'preted 

 the nature of certain structures described in that paper. At the 

 time that I wrote, hardly anything "as known of the structure of 

 the male reproductive organs in exotic Lumbricidae ; the only paper 

 on the subject, however, appeared to show that in Peric/ieeia at any 

 rate' the so-calleJ testes of Perrier and other writers were really 

 the equivalents of the seminal vesicles of Lumbricus, and that the 

 testes of the latter were represented by homologous structures. Since 

 then Mr. Benhanrand Prof. Bergh^ have brought forward conclusive 

 evidence that the structure of the male generative organs in Micro- 

 chceta and Perichata is esseutially similar to tiiose of Lumbricus. 

 In both genera there are two pairs of testes, which become enveloped 

 by the seminal vesicles. My own investigations into the structure 

 of Eudrilus {antea, p. 380), and a genus to be described in a future 

 paper, lead me to confirm in every point thejustice of the conclusions 

 arrived at by Benham and Ikrgh. In the light of these researches 

 I have again examined the structure of the male reproductive organs 

 ill Acanthodrilus dissimilis, and have to make the following additions 

 to and corrections of n)y former paper. 



In the woodcut which illustrates that paper I have figured two 

 pairs of glands, situated in the 1 1th and 12th segments respectively, 

 and attached to the anterior mesenteries of these segments and to 

 the vasa del'erentia at the point where they perforate the mesenteries 

 (fig. 3). I find that I have omitted both in the figure and in the de- 

 scription (p. 824) which accompanies it another pair of glands, whicli 

 are situated on the anterior mesentery of segment lU; the accom- 

 panying drawing (fig. 2, p. 388), which is an alteration of the original 

 woodcut, illustrates this point. The three pairs of glands are closely 

 similar in structure to each other and to the ovaries, which occupy a 

 similar position in segment 13. In my paper already referred to, I 

 noted the fact that the glands which are situated in segment 12 not 

 only agree in structure with the ovaries, but that in one specin.en at 

 any rate they contained fully developed ova. This fact (which I have 

 since verified by a renewed examination of the specimens) led me 

 to infer that the glands, both of this segment and of the one in front, 

 were a rudimentary pair of ovaries wliich j'crhaps never reached 

 maturity. In the light of recent researches — I refer to those of 



^ E. Horst, Niederl. Archiv f. Zool. loc. cit. 



» Quart. Journ. Micr. Sci. 1886. ^ Zeitschr. 1'. wiss. Zool. 1886. 



