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Show 1887-] ANATOMY OF EARTHWORMS. 387 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 the 10th segment, "une sorte de toute petite masse glandulaire, 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 reexamining m y preparations, I find that 1 have misinterpreted the nature of certain structures described in that paper. At the time that I wrote, hardly anything was known of the structure of the male reproductive organs in exotic Lumbricidae ; tbe only paper on the subject, however, appeared to show that in Perichata at any rate1 the so-called 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. Benham2 and Prof. Bergh3 have brought forward conclusive evidence that the structure of the male generative organs in Micro-chata and Perichata is essentially similar to those of Lumbricus. In both genera there are two pairs of testes, which become enveloped by the seminal vesicles. M y own investigations into the structure of Eudrilus (antea, p. 380), and a genus to be described in a future paper, lead m e to confirm in every point the justice of the conclusions arrived at by Benham and Bergh. In the light of these researches I have again examined the structure of the male reproductive organs in Acanthodrilus dissimilis, and have to make the following additions to and corrections of m v former paper. In the woodcut which illustrates that paper I have figured two pairs of glands, situated in the 11th and 12th segments respectively, and attached to the anterior mesenteries of these segments and to the vasa deferentia at the point where they perforate the mesenteries (fig. 3). I find that 1 have omitted both in the figure and in the description (p. 824) which accompanies it another pair of glands, which are situated on the anterior mesentery of segment 10 ; the accompanying 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 m y 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 specimen at any rate they contained fully developed ova 1 his 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 which perhaps never reached maturity. In the light of recent researches-I refer to those of I ^SttS'ltt?' l°°- " ^ ^chr. f. wiss. Zool. 188, |
