character, under the influence of a tropical climate. The
species figured on the last page is brownish-olive on the upper surface,
with numerous greenish-white round spots, darkening towards the edges.
The anterior annulations of the tail are black and white, the posterior
entirely black. Its mouth is transverse and paved with a band of
flattened teeth calculated to crush the hard shells of the animals on
which it feeds. It moves slowly along the bottom in search of its food,
which consists of crustacea and mollusca, and seems to be unable to
catch fishes or other quickly moving animals. Specimens have been taken
near Ceylon, of six feet in width. Like most deep-sea fishes, the ray
has a wide geographical range, and occurs not only in all the Indian
Ocean, but also in the tropical tracts of the Atlantic.

[Illustration: THE RAY (AETOBATES NARINARI).]

[Footnote 1: _Raja narinari_, Bl. Schn. p. 361. _Aetobates narinari_,
Muell. und Henle., Plagiost. p. 179.]

Another armed fish, renowned since the times of AElian and Pliny for its
courage in attacking the whale, and even a ship, is the sword-fish
(_Xiphias gladius_).[1] Like the thunny and bonito, it is an inhabitant
of the deeper seas, and, though known in the Mediterranean, is chiefly
confined to the tropics. The dangerous weapon with which nature has
equipped it is formed by the prolongation and intertexture of the bones
of the upper jaw into an exceedingly compact cylindrical protuberance,
somewhat flattened at the base, but tapering to a sharp point. In
strange inconsistence with its possession of so formidable an armature,
the general disposition of the sword-fish is represented to be gentle
and inoffensive; and although the fact of its assaults upon the whale
has been incontestably established, yet the motive for such conflicts,
and the causes of its enmity, are beyond conjecture. Competition for
food is out of the question, as the Xiphias can find its own supplies
without rivalry on the part of its gigantic antagonist; and as to
converting the whale itself into food, the sword-fish, from the
construction of its mouth and the small size of its teeth, is quite
incapable of feeding on animals of such dimensions.

[Footnote 1: AELIAN tells a story of a ship in the Black Sea, the bottom
of which was penetrated by the sword of a _Xiphias_ (L. xiv. c. 23); and
PLINY (L. xxxii. c. 8) speaks of a similar accident on the coast of
Mauritania. In the British Museum there