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Show 186 MR. M. F. WOODWARD O N [Mar. 1, condition, and possibly have not thus far been functional, although the large size of the cells in some of them does not preclude the possibility of their future maturity. With regard to the oviducts, although the specimen was most carefully dissected and thoroughly examined, only one pair of these ducts was to be seen, and that in the position of the typical single pair of the normal worm: that is, related to the mesentery between the 13th and 14th somites, opening into the body-cavity of the former and on to the exterior on the latter. And neither externally nor internally could any trace of accessory oviducts be discovered. It is interesting to note in Bergh's1 description of the presence of additional ovaries that he, being unable to discover additional oviducts, concluded that the ova from the supernumerary ovaries must necessarily be lost. This might probably be the case with some of the ova, but if many were shed into the body-cavity (as would happen supposing all these ovaries to be functional), it seems possible that some would find their way through the circum-neural arcade, which puts the various subdivisions of the body-cavity into communication with one another, and through which the perivisceral fluid circulates; and, if so, there would seem to be no difficulty in their finding their way into the 13th somite, and then out through the oviducts. Beddard2 has recently shown reason to believe that "in Acantho-drilus the genital funnels and a portion at least of the ducts are formed out of nephridia," and though not definitely proved for Lumbricus, it is probable that they are there formed by a modification of the same process. In view of this it seems strange that an animal so rich in ovaries, and with so much material in the way of segmental organs out of which to fashion oviducts, should have only developed a single pair. Passing from Lumbricus to the allied genera, it is not so rare to find the animal normally possessing two pairs of these glands. Beddard has described a number of such forms. Thus, Perionyx3 has normally two pairs of ovaries, and is further interesting from the fact that these structures vary in position from the 9th to the 16 th segment. Phreoryctes 4 & 5 and UrochcetaG possess two pairs of ovaries, situated respectively on segments 12 and 13. Also in Eudrilus7, Acanthodrilus", and Phreodrilus* Beddard finds strong evidence for the belief that they also possess an additional pair of ovaries. 1 Loc cit. p. 308, footnote. 2 " O n the Homology between the Genital Ducts and Nephridia in the Oligochajta," P. R. S. Lond. 1890, p. 452. :i " On a new and little-known Earthworm, with an account of the variations of Perionyx excavatus," P. Z. S. 1886, p. 308. 4 " Affinities of Phreoryctes," T. R. S. Ed. vol. xxxv. p. 629. 5 " Reproductive Organs of Phreoryctes," Ann. & Mag. Nat. Hist. ser. 6 i. p. 389 (1888). 6 " Certain Points in the Structure of Urochceta," Q. J. M S n s vol xxix p. 235. 7 " On the Anatomy of Earthworms," Q. J. M . S. n. s. vol xxx p 4°1 s " On Phrcodrilus? T. R. S. Ed. vol. xxxvi. (1890) p. 287." |