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CARTILAGINEI.—RAIADÆ.

Ray, the whole canal of whose intestine is not more than half as long as the stomach."

3. Raiana. The Skates. The rhomboidal or lozenge-shaped outline, is eminently characteristic of this group, which is the most numerous of the whole. The tail is moderately long and slender; furnished with two small dorsals, and generally terminated by a small caudal. The skin on the upper parts, particularly of the tail, is generally studded with asperities, tubercles, or curved prickles, but never armed with a long, serrated bony spine. Eleven of our British species belong to this group.

4. Trygonina. The Sting-rays. In these the head is surrounded and inclosed by the pectoral fins; the disk is somewhat rounded; the tail is long, and drawn out to a fine point; it is quite destitute of fins, but is armed near its base with a long and sharp, flattened, bony spine, the two sides of which form thin edges, cut into close, acute teeth,—a most formidable weapon. We have one British species, commonly called the Fire-flaire, of which Mr. Couch thus speaks. "The manner in which it defends itself shows its consciousness of the formidable weapon it carries on its tail. When seized or terrified, its habit is to twist its long, slender, and flexible tail round the object of attack, and with the serrated spine tear the surface, lacerating it in a manner calculated to produce violent inflammation." Other authors state that it is capable of striking its weapon with the swiftness of an arrow into its prey or its enemy, when, with its winding tail, it secures its capture.

5. Myliobatina. The Eagle Rays. The pec-