The Descent of Man

cal fishes differ sexually in colour and structure;
and there are some striking cases with our
British fishes. The male Callionymus lyra has
been called the gemmeous dragonet "from its
brilliant gem-like colours." When fresh caught
from the sea the body is yellow of various shades,
striped and spotted with vivid blue on the
head; the dorsal fins are pale brown with dark
longitudinal bands; the ventral, caudal, and
anal fins being bluish-black. The female, or
sordid dragonet, was considered by Linnaeus,
and by many subsequent naturalists, as a distinct
species; it is of a dingy reddish-brown,
with the dorsal fin brown and the other fins
white. The sexes differ also in the proportional
size of the head and mouth, and in the position
of the eyes (12. I have drawn up this description
from Yarrell's 'British Fishes,' vol. i. 1836,
pp. 261 and 266.); but the most striking difference
is the extraordinary elongation in the
male (Fig. 29) of the dorsal fin. Mr. W. Saville
Kent remarks that this "singular appendage