is constantly in motion. It has a long tail, scaly and flattened at the sides; membranous feet; eyes very small; and no external ears. This animal is very common along the rivers and lakes of Southern Russia, where it feeds on worms, the larvae of insects, and particularly on leeches, which it easily withdraws from the mud by means of its flexible proboscis. It never comes voluntarily on shore, but is often taken in the nets of the fishermen. Its burrow, excavated in a bank, commences under water, and ascends to above the level of the highest floods. Under the tail of the Desman are two small follicles containing a kind of unctuous substance, of a strong musky odour, from which the name of Musk-rat is given to it.

DEW [MOTHS). A name given by collectors to Moths of the genus Setina.

DIADEM SPIDER. (Epeira diadema.) This spider, so common in the autumn, belongs to Walckenaer's genus Epeira. Its body, when full grown, is nearly as large as a hazel nut, is of a deep chestnut brown colour, and

DIADEM SPIDER.-(EPEIRA DIADEMA.) the abdomen beautifully marked by a longitudinal series of round milk-white spots, crossed by others of a similar appearance, so as to represent in some degree the pattern of a smali diadem. It is chiefly seen during the autumnal season in our gardens, where, in some convenient spot or shelter, it forms a large, round, close web of yellow silk, in which it deposits its eggs, guarding this web with a secondary one of a looser texture. The young are hatched in the ensuing May, the parent insects dying towards the close of autumn. At the tip of the abdomen are placed five papillæ or teats, through which the spider draws its thread. The eyes, which are situated on the upper part of the thorax, are eight in number, placed at a small distance from each other. The fangs with which the animal wounds its prey are strong, curved, sharp-pointed, and each furnished on the inside, near the tip, with a small oblong hole or slit, through which is discharged a poisonous fluid into the wound made by the point itself. The feet are of a highly curious structure; the two claws with which each is terminated being furnished on its under side with several parallel processes resembling the teeth of a comb, and enabling the spider to manage with the utmost facility the threads in its web, &c. [See SPIDER.]

DIAMOND BEETLE. (Entimus.) This splendid Coleopterous insect belongs to the

family Curculionide, and contains two or three species. It is very abundant in some parts of South America. It is often, with a magnifying glass of no great power, formed

DIAMOND BERITE (ENTIMUS NOBILIS.)

into a very pleasing toy to amuse young people. There are small species of Curculioide in our own island, however, which are scarcely less brilliant when magnified under a good light, and with sufficient power.

DIAPERIS. A genus of Coleopterous insects. [See TAXICORNES.]

DICEUM. A genus of Tenuirostral Birds, allied to the CREEPERS: they do not use their tails as these birds do; and they are generally brilliant in colour, having more or less of scarlet in their plumage. Different species are found in Asia and its islands, and also in Australia.

and Cyphonocephalus, from India, and Micterystes and l'hadimus, from the Eastern Islands, the active researches of Indian officers and colonists will make these pretty and singular insects more common.

DIDELPHIDE. A family of quadrupeds belonging to the order Marsupialia, and consisting of the genus Didelphis, or Opossum. They are restricted to America. They are characterized by having ten incisors above and eight below, the canines being one on each side of either jaw, and the molars seven, the four last, or true molars, being crowned with sharp tubercles. The limbs are short; the feet plantigrade; and the toes, which are five on each foot, armed with sharp, strong, curved claws, except the inner toe or thumb on the hinder feet, which is opposable and destitute of a nail. The tail, except at the base, is scaly and naked; and it is usually more or less prehensile. In some species the pouch is entirely wanting, being indicated only by a slight fold of the skin. [See OPOSSUM.]

DIDUNCULUS. A genus of birds found in the South Sea Islands. [See GNATHODON.]

DIDUS. A genus of birds now extinct. [See DoDo.]

DIMERA. A section of the order Homoptera, comprising much smaller insects than those included in the section Trimera, and distinguished from them by having only two joints in the tarsi; with antennæ longer than the head, and composed of from six to ten filiform joints; whilst they differ from the Monomera by the winged individuals possessing four wings, the anterior being ordinarily of the same membranous texture as the posterior. The section consists of the families Psyllido, Aphide, and Aleyrodidae.

DIMYARIA. The name given to the second order of Conchifera, or Bivalve Shells. It contains a great number of families, which may be grouped into four divisions, arising partly from the shape of the foot of its molluscous inhabitant, but chiefly from the more or less perfect manner in which the valves close upon each other. Sometimes the term Bimusculosa is given to this order. DINGO, or AUSTRALIAN DOG. This species of the canine race has a very wolflike appearance. The ears are short and erect; the tail rather bushy; the hair, which

has the same sort of snarling and howling voice as the larger kind of dogs have in general; though by some it has been erroneously said neither to bark nor growl. There is good reason, however, to believe once domesticated, which has returned to that the Dingo is the descendant of a race its wild state.

DINORNIS. A genus of birds allied to the Ostrich tribe, now only found in a fossil state in New Zealand, whence many bones have been sent to this country. One of the species must have been at least fourteen feet high, and it is believed that some specimens may have been still higher. Our space will not allow of our entering into the interesting details of comparative anatomy, which Professor Owen has given in his elaborate Memoir in the Tranactions of the Zoological Society-to which the reader is referred. It is known to the natives by the name of Moa.

DINOTHERIUM. A genus of extinct herbivorous quadrupeds, of gigantic dimensions; but as only fragments of this huge creature have yet been found, the size of the entire animal cannot be accurately given.

SKULL OF DINOTHERIUM GIGANTEUM

A skull of one was disinterred at Epplesheim, in Hesse Darmstadt, in 1836, measuring about four feet in length and three in breadth; from which, according to the calculations of Cuvier and Kaup, the Dinotherium is supposed to have attained the length of eighteen feet. Dr. Buck land, who paid great

attention to the remains of this immense specimen of extinct Mammalia, is decidedly of opinion that it was an aquatic animal. "It is mechanically impossible," he observes, "that a lower jaw, nearly four feet long, loaded with such heavy tusks at its extremity could have been otherwise than cumbrous and inconvenient to the quadruped living on dry land. No such disadvantage would have attended this structure in a large animal destined to live in water; and the aquatic habits of the family of Tapirs, to which the Dinotherium was most nearly allied, render it probable that, like them, it was an inhabitant of fresh-water lakes and rivers," &c. The Doctor subsequently

says," Professor Kaup and Dr. Klipstein have recently published a description and figures of this head, in which they state that the very remarkable form and dispositions of the hinder part of the skull show it to have been connected with muscles of extraordinary power, to give that kind of movement to the head which would admit of the peculiar action of the tusks in digging into and tearing up the earth. They further observe that my conjectures respecting the aquatic habits of this animal are confirmed by approximations in the form of the occipital bone to the occiput of Cetacea; the Dinotherium, in this structure, affording a new and important link between the Cetacea and the Pachydermata."

DIODON. A remarkable genus of Plectognathi, or bony fishes with soldered jaws.

The DIODON HYSTRIX, commonly termed the Sea-Porcupine, is of a nearly spherical form, sometimes measuring not less than two feet in length; but it posserres the power of inflating or contracting itself at pleasure by means of an internal skin or membrane situated beneath the exterior or spiny covering. Its colour is a pale grey, the back being of a somewhat deeper cast; and the whole body is marked at the base of each spine by a round black spot; the fins being also spotted. When taken by a line and hook, it inflates its body and elevates its spines to the highest possible degree, as if endeavouring to wound in all directions; nor can it be touched without danger until it is dead. It is a native of the Indian and American seas; and its flesh is coarse and worthless.

The OBLONG DIODON (Diodon atinga) differs from the former in being of a more lengthened shape, and in having the spines rather round than triangular. Its general colour is grey, deeper on the back, and with a cast of pink on the lower parts like the Diodon Hystrix: it is marked with numerous round black spots; but it is only from twelve to fifteen inches in length. Unless very carefully cleaned, it is dangerous to eat it; for if not absolutely poisonous, the flesh is highly unwholesome. It is a native of the Indian and American scas.

Besides the above, there is the RoUND DIODON (Diodon orbicularis), about nine or ten inches in length; which is considered a poisonous fish: PLUMIER'S DIODON (Diodon Plumieri), a species very nearly allied to the Oblong Diodon: and the PATCHED DIODox (Diolon iturosis), which inclines to a globular shape, and is marked on each side of the body with an oval patch and two transverse ones; and on the back a round spot encircling the dorsal fin spines white with brown tips, and all the fins greenish yellow.

"One day," says Mr. Darwin (while on the coast of Brazil), "I was amused by watching the habits of a Diodon, which was caught swimming near the shore. This fish is well known to possess the singular power of distending itself into a nearly spherical form. After having been taken out of water

for a short time, and then again immersed in it, a considerable quantity both of water and air was absorbed by the mouth, and perhaps likewise by the branchial apertures. The process is effected by two methods; the air is swallowed, and is then forced into the cavity of the body, its return being prevented by a muscular contraction which is externally visible; but the water, I observed, entered in a stream through the mouth, which was wide open and motionless; this latter action must therefore depend on suction. The skin about the abdomen is much looser than that of the back; hence, during the inflation, the lower surface becomes far more distended than the upper; and the fish, in consequence, floats with its back downwards. Cuvier doubts whether the Diodon, in this position, is able to swim ; but not only can it thus move forward in a straight line, but likewise it can turn round to either side. This latter movement is effected solely by the aid of the pectoral fins, the tail being collapsed, and not used. From the body being buoyed up with so much air, the branchial openings were out of water: but a stream drawn in by the mouth constantly flowed through them.

"The fish, having remained in this distended state for a short time, generally expelled the air and water with considerable force from the branchial apertures and mouth. It could emit, at will, a portion of the water; and it appears, therefore, probable, that this fluid is taken in partly for the sake of regulating its specific gravity. This Diodon possessed several means of defence. It could give a severe bite, and could eject water from its mouth to some distance, the movement of its jaws. By the inflation at the same time it made a curious noise by of its body, the papillæ, with which the skin is covered, became erect and pointed. the most curious circumstance was, that it emitted from the skin of its belly, when handled, a most beautiful carmine red and fibrous secretion, which stained ivory and paper in so curious a manner, that the tint is retained with all its brightness to the present day.

But

DIOMEDEA. A genus of Palmiped birds. [See ALBATROSS.]

DIOPSIS, or TELESCOPE FLY. A very singular genus of Dipterous insects, remarkable for the enormously developed pedicels on which the eyes are situated. They

TELESCOPE FLY.

(DIOPSIS MACROPHTHALMA.)