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Show 184 MR. M. F. WOODWARD ON [Mar. 1, 2. Description of an Abnormal Earthworm possessing Seven Pairs of Ovaries. By M. F. W O O D W A R D, Demonstrator of Zoology, Royal College of Science, London1. [Received February 29, 1892.] (Plate XIII.) Abnormalities affecting the genitalia of the Earthworm are of un-frequent occurrence, and, when such variations occur, they, as a rule, only affect accessory structures like the spermathecae and seminal vesicles, not essential ones such as the genital glands. One or two cases have, however, been put upon record in which the genital glands were themselves affected, although these variations were but slight ones. One case is described by Benham2, in which the ovary of the right side was situated on the 12th somite; this might at first sight appear to be a simple shifting forward of the ovary, especially as the oviduct and the posterior termination of the vas deferens of that side are also displaced on to the segment in front of that on which they are normally situated. But when compared with the specimen which I now propose to describe it would appear more piobable that the right ovary of Benham's specimen does not correspond with the normal one, but is rather a fresh structure altogether. Bergh3 has also described three abnormal specimens, viz. two L. turgidus and one L. purpureus, which are of great interest in having undergone an actual reduplication of the ovaries, being possessed of an additional pair on segment 14, the normal ovaries being present as usual on segment 13. The above-cited cases are, as far as I can ascertain, the only recorded cases of variations in the position and number of the ovaries in Lumbricus. The specimen which forms the subject of the present communication was a large, well-developed common Earthworm (Allolobophora, sp. inc.), possessing a well-marked clitellum; it was killed early in November, in which month the genitalia are generally but poorly developed. With the exception of the ovaries the genital organs were quite normal. O n the removal of the alimentary canal one immediately noticed a number of small pear-shaped bodies (Plate XIII. fig. 1, ov.1'1) projecting backwards from the mesenteries of the segments 11-17. These paired bodies are situated one on either side of the longitudinal nerve-cord, and attached to the posterior face of the mesenteries by their expanded bases, while their apices project back freely into the cavities 1 Communicated by Prof. G. B. HOWES. 2 " Note on a couple of Abnormalities," Ann. & Mag. Nat. Hist. 6th series vol. vii. (1891) p. 256. 3 " TJeb. d. Bau u. d. Entwicklg. d. Geschlechtsorg. d. Regenwurmer " Zeitschr. fur wiss. Zool. 1886, vol. xliv. p. 303. |