to be easily detached from each other. A plate varies in thickness from an eighth to a quarter of an inch, according to the size and age of the animal.

For the following account of the manner in which this beautiful material is rendered available to the many purposes of use and ornament which it subserves, we are indebted to the history of British Reptiles by Professor Bell.

"The scales, or plates, are in the first place separated by the application of heat. They are sold to the manufacturers in the rough state, in which they are uneven, fragile, opaque, and dirty; and it is the first object of the artificer to obviate these defects. The uneven surface, the irregular curvature, the unequal thickness of different parts, have all to be corrected: and not only can these objects be readily effected, but the substance can be rendered ductile, compressible, capable of receiving any impression, of being carved, moulded, and polished, and even extended by soldering pieces together by means of their own substance reduced to powder. The whole of these processes are performed by means of heat.

"The uneven curvature is first of all to be removed, and the plate rendered perfectly flat. This is effected by immersing it in hot water, and then allowing it to cool under heavy pressure, between smooth blocks of wood, or metallic plates. The surface is then rendered smooth, and the thickness equal, by scraping and filing away the rough and prominent parts. In this way each plate receives an equal and smooth surface. But it is in many cases desirable to employ larger pieces than can be obtained from single

plates, and two pieces are then united together in the following manner :-The edges are bevelled off to the space of two or three lines, and the margins, when placed together, overlap each other to that extent. They are then pressed together by a metallic press, and the whole is submitted to the action of boiling water; and by this means the two pieces are so perfectly soldered together, as to leave no indication of the line of union. By the application of heat, also, the tortoise-shell may be made to receive any impression, by being pressed between metallic moulds.

"No portion of this precious substance is lost or useless. The filings and powder, which remain after these and the other processes to which the shell is submitted, are placed with any small fragments in metallic moulds, and by means of pressure, exercised whilst they are exposed to the heat of boiling water, they are formed into plates of any thickness which may be required."

The shell of the Turtle being so valuable, some ingenuity is well bestowed in the endeavour to avoid any waste of it. Accordingly, in manufacturing combs, a curious invention has been resorted to for this end. To make a comb six inches long, and one inch wide, one would naturally suppose that it would be needful to have a piece of shell of that size; and such is indeed the case. But two combs may be formed out of a piece

COMB-CUTTING.

of shell very little larger, by merely resorting to a very simple plan, which the accompany

ing diagram will clearly illustrate. The shell is cut by a circular saw, in the manner represented in the zigzag lines; thus, when the sawing is completed, the shell can be pulled in two, and the teeth of the combs will be cut out of one another, while the solid margins are left to form the backs.

Besides the localities already named as the resorts of the Hawksbill Turtle, we may mention the West Indian Isles, those of Bourbon and Mauritius, the Seychelles, and most of the situations enumerated in the notice of the Green Turtle. On three occasions it has occurred on the shores of our own country. Sibbald received the shell of one which came into Orkney. Fleming records its having been taken at Papa Stour, one of the West Zetland Isles; and Dr. Turton mentions one which was taken in the Severn in, the year 1774, and placed in his father's fishponds, where it lived till the following winter.

ORDER II. LORICATA.

(Crocodiles.)

The appellation by which this Order is distinguished, derived from the word lorica, signifying a coat of mail, expresses the most obvious peculiarity by which its members may be known, the ridged and bony armour in which they are invested. "The Crocodiles and Alligators of both worlds, and the Gavials of India, which constitute this order, are distinguished," observes Mr. Bell, "from the true Saurians or Lizard tribe, by several important characters. Of these the most tangible and obvious is that upon which the name of the Order is founded; the covering of the whole of the back part of the neck, body, and tail, with distinct series of bones, of modederate size, imbedded, as it were, in the substance of the skin, and covered externally with a thick cuticle. These dermal bones are usually furnished with a crest, which renders them exceedingly strong, and they altogether form a panoply of defence which can resist the attacks of the most powerful enemies of whatever kind."*

The general form of the Loricata agrees with that of the Lizards; but besides the important difference already mentioned, the bony plates run down the body in longitudinal lines, the structure of the skull is much more solid, and the posterior orifice of the body is longitudinal. The tail is * British Reptiles, xix.

flattened at the sides; there are five toes before and four behind, of which the innermost three on each foot are armed with claws; the toes are connected by intervening membranes, varying in extent. There is a single row of pointed teeth in each jaw; the tongue is fleshy, flat, and free only at the extreme edge; whence the Crocodile was vulgarly reputed to be without a tongue. The back and tail, as already intimated, are covered by large and strong scales of square form, elevated into a ridge in the middle; the tail is surmounted by a deeply notched deeply notched or saw-like crest, which is double at the base; the scales of the belly are delicate and smooth. The nostrils are situated at the end of the muzzle, and open by small crescent-form slits, closed by valves; they lead through a long and straight canal pierced in the bones of the palate, to the back of the mouth. The lower jaw is prolonged behind the skull, and this structure causes the upper jaw to seem moveable; but this is simply an illusion. The external ear is closed at pleasure by means of two fleshy lips; the eye is furnished with three lids: two small glandular orifices are placed beneath the throat, whence exudes a musky secretion, the odour of which strongly marks these animals even for years after their dried skins have been preserved in a museum.

The Reptiles of this Order are of large size and great strength; and as they are exclusively carnivorous and predaceous, and very ferocious, they are dreaded, not without reason, in the tropical countries which they chiefly inhabit. Yet these creatures, feared and hated as they are, were not created in vain. "In the grand policy