the cheek-pouches. The animals usually remain at the surface of the water, with the head slightly raised above it; but upon the slightest alarm they instantly disappear; and they are so watchful of danger, that the mere act of levelling a gun is sufficient to cause them to dive. After some little time, they reappear at some distance from the spot where they sank. Their burrows are excavated in the banks of the streams they inhabit, and are of very curious construction. The entrance is situated near the water's edge, on a steep part of the bank; and is concealed amongst the herbage. It gradually rises from the level of the stream, proceeding in a serpentine direction to a distance of twenty or even fifty feet from the entrance; and its termination is enlarged, so as to form a kind of nest for the parents and their offspring, which is strewed with dry river-weed. The burrows have usually a second orifice, below the surface of the water; communicating with the passage just within the upper entrance.

319. The young are produced in a very imperfect state, and are very unlike the fully-developed animal. The skin is entirely destitute of fur, and is thrown, by the curling of the body, and the doubling of the head and tail beneath it, into transverse folds; the eyes are not formed, and their place is merely indicated by the presence of a few wrinkles on the skin. The margin of the bill is at that time soft, and the tongue (which in the adult does not extend between the mandibles) advances to its front edge; so that the young animal can obtain nourishment by sucking, which was at first thought impossible. The mammary gland of the female is very simple in structure, and is divided into a large number of separate lobes; this is just what might be expected, when it is remembered that the organ here makes its first appearance, and presents therefore its lowest grade of formation (ANIM. PHYSIOL., § 358). The Ornithorhyncus is truly ovo-viviparous; for the embryo appears never to derive any other sustenance from its parent, up to the time of its birth, than that which is stored up for it in the ovum; but, as in some Lizards and Fishes, the egg is hatched (as it were) within the oviduct, so that the young is born alive. In consequence of its imperfect condition, however, it cannot leave its burrow or nest

ORNITHORHYNCUS, ECHIDNA.

357

young

for some time; and this serves for the protection of the Ornithorhyncus, as the pouch of the Opossum or Kangaroo does to its helpless offspring. A very interesting account has been given by Mr. G. Bennet,* of the habits of some of these animals, which he kept in a state of captivity, during his residence in Australia. The Ornithorhyncus appears from this statement to be a lively interesting creature. Its voice, which it utters when alarmed or disturbed, resembles the growl of a puppy, but in a softer key. It dresses its fur, combing it with its feet, and pecking at it with its beak; and seems to take great delight in keeping it smooth and clean. When asleep, it sometimes rolls itself up like a hedgehog, or curls itself like a dog, keeping its back warm by bringing over it the flattened tail. The young are playful, and gambol with one another in a very animated manner. They appear to be in a great measure nocturnal, preferring the twilight to the glare of day. They may be fed upon bread soaked in water, chopped egg, and meat minced very small. Two species have been described, differing slightly in colour; but it is doubtful whether these are more than varieties. The Ornithorhyncus is confined to New Holland and Van Diemen's Land.

320. The Echidna, or Porcupine Ant-eater, seems at first

sight very different in its conformation from the Ornithorhyncus; but in the most important particulars of its structure it closely resembles it, though differing widely in its habits, and in all the peculiarities connected with them. It is

about the size and form of a Hedgehog, which it also resembles in having its body covered with spines; but these are much

Transactions of the Zoological Society, Vol. I.

stouter than in that animal; and the two are easily distinguished by the long narrow snout which the Echidna possesses. This snout is formed by the elongation of the muzzle, and is cleft at the point by a very small mouth. The jaws are destitute of teeth, as in the true Ant-eater (§ 250); and the tongue is long and slender, and capable of being protruded to a considerable distance. The legs are short, but large and strong; and both the hind and fore-feet possess five toes, which are armed with strong slightly-curved claws. On the heel of the hind-foot is a curved horny spur, like that of the Ornithorhyncus. The Echidna is a burrowing animal; and the broad strong claws of its fore-feet appear to be used for digging out the earth; while the large hollow claws of the hind-feet are to enable the animal to cast away the loose soil. These members are twisted, and directed obliquely backwards, in such a manner that the sides of the claws lie on the ground, and the concave surface or sole of the foot is behind; thus forming very efficient shovels for this purpose. The skin of the Echidna is remarkably thick, to give attachment to the strong spines with which it is covered; and it can erect these in the manner of a Hedgehog, though unable to roll itself into a ball, like that animal. The spines are intermingled with coarse hairs, which also clothe the limbs and under surface of the body. This animal lives entirely upon insects; which it obtains, in the same manner with the Ant-eaters, by entrapping them with the viscous secretion that covers its long tongue. It inhabits the mountain ranges of Australia, and is found also in Van Diemen's Land and the islands of Bass's Straits. It burrows with great rapidity; and will even work its way under a pretty strong pavement, or the foundation of a wall, removing the stones with its claws. When attacked by dogs, it quickly sinks itself in the earth or sand, so as to present nothing but its prickly back to its adversaries. In one instance, a large chest of earth containing plants being given to an Echidna in captivity, it made its way to the bottom in less than two minutes. This individual is described as stupid and inert; and for the first month after its capture, it took no food whatever. It became very thin, but did not appear to suffer. It afterwards

ate a mixture of flour, water, and sugar, upon which it lived for some time. It made frequent efforts to get out of its cage, and displayed very great strength. The possessor of another captive Echidna speaks of it as in his opinion the strongest Quadruped, for its size, in existence. To lift it from the ground requires. more force than would be supposed; so firmly does it fix itself to the earth, by means of its powerful feet and claws. The animal is now very rare; and but little is known of its habits in a state of nature. Two species or varieties of it have been found.

321. The following Table, constructed by Professor Owen,* is designed to express the connexions of the several orders of Mammalia with each other, and the points at which they are most nearly related to the inferior Vertebrata. The names of the orders are printed in small capitals; and those of the connecting genera in italics. Where the union is by a continuous line, it is intended to show that the connexion is very close; but where the line is dotted, or a blank space is left, the links are more or less wanting. Thus the order QUADRUMANA is closely connected with the CHEIROPTERA by the Galeopithecus (§ 163); with the CARNIVORA by the Lemur (§ 161); with the RODENTIA by the Cheiromys (§ 164); with the MARSUPIALIA by the Didelphis (§ 309) ;and less closely with the EDENTATA by the Bradypus (§ 240), which approaches the QUADRUMANA in certain particulars. Again, the CARNIVORA and the CHEIROPTERA are connected by the INSECTIVORA; and the former are united to the CETACEA by the genus Otaria, or Fur-Seal (§ 202). The EDENTATA are connected with the PACHYDERMATA by the fossil Glyptodon (§ 247); and this last order is connected with the RODENTIA by the fossil Toxodon (§ 303). With the RoDENTIA, again, the RUMINANTIA are connected by the genus Moschus (§ 276).

* Cyclopædia of Anatomy, Vol. III. p. 245.