The Double-fish, here represented, is a pair of Cat-fish, which were taken alive in a shrimp-net, at the mouth of Cape Fear River, near Fort Johnston. North Carolina, in 1833, and presented to Professor Silliman. One of them is three and a-half, and the other two and a-half inches long, including the tail--the smallest emaciated, and of sickly appearance. They are connected in the manner of the Siamese Twins, by the skin at the breast, which is marked by a dark streak at the line of union. The texture and colour otherwise of this skin is the same as that of the belly. The mouth, viscera, &c., were entire and perfect in each fish; but, on withdrawing the entrails, through an incision made on one side of the abdomen, the connecting integument was found to be hollow. A flexible probe was passed through from one to the other, with the tender and soft end of a spear of grass, drawn from a green plant. But there was no appearance of the entrails of one having come in contact with those of the other, for the integument was less than one-tenth of an inch in its whole thickness; in length, from the body or trunk of one fish to the other, it was three-tenths; and in the water, when the largest fish was in its natural position, the small one could, by the length and pliancy of this skin, swim in nearly the same position. When these fish came into existence it is probable they were of almost equal size and strength, but one "born to better fortune," or exercising more ingenuity and industry than the other, gained a trifling ascendency, which he improved to increase the disparity, and, by pushing his extended mouth in advance of the other, seized the choicest and most of the food for himself. From the northern parts of British America we have received extraordinary contributions to our fish collections. One of these is the Square-browed Malthe, obtained in one of the land expeditions under the command of Captain Sir John Franklin. R.N. It was taken on the Labrador coast, and then belonged to a species hitherto undescribed. Its intestines were filled with small crabs and univalve shells. The extreme length of the fish is 7 inches 11 lines. The upper surface is greyish white, with brown blotches, and the fins are whitish. The head is much depressed and greatly widened; the eyes far forward; the snout projecting like a small horn. Most of the fish of this family can live long out of water, in consequence of the smallness of their gill-openings; indeed, those of one of the genera are able, even in warm countries, to pass two or three days in creeping over the land. All the family conceal themselves in the mud or sand, and lie in wait to take their prey by surprise. The accompanying engraving is from the very able work of Dr. Richardson, F.R.S., published by the munificence of Government. [Illustration: SQUARE-BROWED MALTHE AND DOUBLE FISH.]