52

Scientific Memoirs by

      Wilson, Pro. Roy Soc. Edinb. XX, 1895, p. 309 (Reproduction of Cancer pagurus).

      Brandes, Biol. Centralblatt, XVII, 1897, p. 346 (Galathea strigosa and Eupagurus
prideauxii: Dromia and Maia also mentioned).

      3. On Certain Primary Sexual Characters in Certain Bony Fishes.

      A good many Teleostei are known to be viviparous, and in the males of
these viviparous species various organs of impregnation, such as modified fin-
rays, post-anal papillæ, etc., have been described.

      The " Investigator " has discovered three species of Bony Fishes, belonging
to the family Ophidiidœ, which possess intromittent male organs of the post-
anal-papilla type, of remarkable size and complexity. These three Ophidioids
are Diplacanthopoma raniceps, Hephthocara simum, and Saccogaster maculata.

      In Diplacanthopoma raniceps the male organ is very large, its free portion,
in a fish about six inches long, standing clear of the abdomen for about a quarter
of an inch. A description and figure of the organ will be found in Ann. Mag.
Nat. Hist. for August 1898, p. 155, and in pl. xxvi of the Illustrations of the Zo-
ology of the Investigator: Fishes. Its walls are of cartilaginous consistence, es-
pecially at the apex, and its cavity is lined by thickened peritoneum, so that it is a
sort of hernia of the body-cavity. Its free end is thrown into folds of remarkable
intricacy: the posterior folds form a capacious " personate" sac, into the depth
of which the testes open: the anterior folds enclose a smaller cavity, which is
nearly filled by a pair of projecting papillæ.

      The corresponding organ of the female is a prominent cone, also lined by
peritoneum, and lodging the ends of the ovaries: these have a common opening of
large size, at the spongy apex of the cone.

      In Hcphthocara simum the male organ exactly resembles that of Diplacan-
thopoma raniceps in all but size:the female organ, however, is not so prominent.

      In Saccogaster maculate the male organ, which is relatively smaller than
that of Diplacanthopoma raniceps, is bilobed, with—in a well preserved speci-
men—a long filament standing in the crevice between them: the testes open bet-
ween and behind the lobes. In the female of this species the skin round the
single large genital orifice is thickened and spongy, but there is no special prom-
inence. The male organ is figured illustrations of the Zoology of the Investi-
gator: Fishes, pl. xxix.

      Not to mention Elasmobranchs, or the curious racemose organ, of doubtful function, of
Plotosus, the following papers, in addition to some of those quoted in the paragraphs on
Viviparlty in Bony Fishes, relate to this subject:—

           Hyrtl, in Denk. Kais. Akad. Wien, I, 1850, p. 391, pl.lii, liii.

           Blake, Proc. Calif. Acad. Nat. Sci., III, 1868, p. 371.