on their heads, and several rows along the upper outer surface of
their pectoral fins. These are present in the males of some species,
which have other parts of their bodies smooth. They are only
temporarily developed during the breeding-season; and Dr. Gunther
suspects that they are brought into action as prehensile organs by the
doubling inwards and downwards of the two sides of the body. It is a
remarkable fact that the females and not the males of some species, as
of Raia clavata, have their backs studded with large hook-formed
spines. (1. Yarrell s Hist. of British Fishes, vol. ii. 1836, pp 417,
425, 436. Dr. Gunther informs me that the spines in R. clavata are
peculiar to the female.)
The males alone of the capelin (Mallotus villosus, one of Salmonidae),
are provided with a ridge of closely-set, brush-like scales, by the aid
of which two males, one on each side, hold the female, whilst she runs
with great swiftness on the sandy beach, and there deposits her spawn.
(2. The American Naturalist, April 1871, p. 119.) The widely distinct
Monacanthus scopas presents a somewhat analogous structure. The male,
as Dr. Gunther informs me, has a cluster of stiff, straight spines,
like those of a comb, on the sides of the tail; and these in a specimen
six inches long were nearly one and a half inches in length; the female
has in the same place a cluster of bristles, which may be compared with
those of a tooth-brush. In another species, M. peronii, the male has a
brush like that possessed by the female of the last species, whilst the
sides of the tail in the female are smooth. In some other species of
the same genus the tail can be perceived to be a little roughened in
the male and perfectly smooth in the female; and lastly in others, both
sexes have smooth sides.
The males of many fish fight for the possession of the females. Thus
the male stickleback (Gasterosteus leiurus) has been described as mad
with delight, when the female comes out of her hiding-place and
surveys the nest which he has made for her. He darts round her in
every direction, then to his accumulated materials for the nest, then
back again in an instant; and as she does not advance he endeavours to
push her with his snout, and then tries to pull her by the tail and
side-spine to the nest. (3. See Mr. R. Warington s interesting
articles in Annals and Magazine of Natural History, October 1852, and
November 1855.) The males are said to be polygamists (4. Noel
Humphreys, River Gardens, 1857.); they are extraordinarily bold and
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