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Show 1883.] PROF. HUXLEY ON THE OVIDUCTS OF OSMERUS. 137 the same series ; that is to say, the abortion of the oviducts, commenced in Osmerus, is completed in Salmo; and all that remains of the primitive arrangement is the fold described by Rathke and the so-called " abdominal pore," which, it will be observed, is the homo-logue of half of the urinogenital opening of the Ganoids, and has Fig. 2. The left ovary and oviduct of Amia culva, half natural size. ov. I, left ovary ; m.o. I, left mesoarium; od. I, left oviduct; od. a, opening of the oviduct into the " bladder." nothing to do with the " abdominal pores " of these fish and of the Selachians. As is well known, Lepidosteus presents an example of a Ganoid with oviducts like those of the higher Teleostei; in Osmerus, on the other hand, we have a Teleostean with oviducts like those of the ordinary Ganoidei. It is tolerably obvious, therefore, taht the cha- 10* |
