The Rays form a large tribe of cartilaginous fishes in which, although the skeleton is not osseous, the development of organs is so advanced that they would appear to be the highest of the class, approaching nearest to amphibians. They are easily distinguished from the sharks by their broad and flat body, the pectoral fins being expanded like wings on each side of the trunk. They are all inhabitants of the ocean, and some grow to a prodigious size. Specimens have been caught of twenty feet in breadth. These, however, are of rare occurrence, as such huge monsters usually retreat into the depths of the sea, where they are secure from the molestation of man. It is, generally speaking, only the young and the smaller species that approach the coasts, where they find a greater supply of those marine animals which form their food. The Rays have been divided into several generic groups, and the one of which a drawing (Aëtobates narinari[3271]) is given, has very marked characteristics in its produced snout, pointed and winged-like pectoral fins, and exceedingly long, flagelliform tail. The latter is armed with a strong, serrated spine, which is always broken off by the fishermen immediately on capture, under the impression that wounds inflicted by it are poisonous. Their fears, however, are utterly groundless,
as the ray has no gland for secreting any venomous fluid. The apprehension may, however, have originated in the fact that a lacerated wound such as would be produced by a serrated spine, is not unlikely to assume a serious 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.
Another armed fish, renowned since the times of Ælian and Pliny for its courage in attacking the whale, and even a ship, is the sword-fish (Xiphias gladius).[3281] 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.
In the seas around Ceylon sword-fishes sometimes attain to the length of twenty feet, and are distinguished by the unusual height of the dorsal fin. Those both of the Atlantic and Mediterranean possess this fin in its full proportions, only during the earlier stages of their growth. Its dimensions even then are much smaller than in the Indian species; and it is a curious fact that it gradually decreases as the fish approaches to maturity; whereas in the seas around Ceylon, it retains its full size throughout the entire period of life. They raise it above the water, whilst dashing along the surface in their rapid course; and there is no reason to doubt that it occasionally acts as a sail.
The Indian species (which are provided with two long and filamentous ventral fins) have been formed into the genus Histiophorus; to which belongs the individual figured on the next page. It is distinguished from others most closely allied to it, by having the immense dorsal fin of one uniform dark violet colour; whilst in its congeners, it is spotted with blue. The fish from which the engraving has been made, was procured by Dr. Templeton, near Colombo. The species was previously known only by a single specimen captured in the Red Sea, by Rüppell, who conferred upon it the specific designation of "immaculatus."[3301]
Ælian, in his graphic account of the strange forms presented by the fishes inhabiting the seas around Ceylon, says that one in particular is so grotesque in its configuration, that no painter would venture to depict it; its main peculiarity being that it has feet or claws rather than fins.[3302] The annexed drawing[3303] may probably represent the creature to which the informants of Ælian referred. It is a cheironectes; one of a group in which the bones of the carpus form arms that support the pectoral fins, and enable these fishes to walk along the moist ground, almost like quadrupeds.
They belong to the family of Lophiads or "anglers," not unfrequent on the English coast; which conceal themselves in the mud, displaying only the erectile ray, situated on the head, which bears an excrescence on its extremity resembling a worm; by agitating which, they attract the smaller fishes, that thus become an easy prey.