CLASS III. REPTILIA: 
ORDEE 1. CHELONIA. 
359 
THE IMBRICATED TURTLE AT SEA. 
" Each turtle lias generally three layings in the season, at intervals of two or three weeks. 
The eggs are perfectly round, varying from two to three inches in diameter. The external mem- 
brane is flexible, very white, and contains a considerable quantity of calcareous matter." 
The Hawk's-Bill Tuetle, C, imhricata^ receiving its popular name from the curved and pointed 
form of the upper jaw, rarely exceeds three feet; its flesh is unwholesome, but as it furnishes the 
well-known Tortoise- Shell of commerce, it is much sought after. Although the greater number 
of the whole order of Chelonia 
haye the back and sternum cov- 
ered with horny plates or scales, 
it is almost exclusively those of 
the present species which are 
applicable to the purposes of 
art. The thirteen plates with 
Avhich the whole upper part of 
the shell is covered, are in fact 
much thicker and stronger, as 
well as more beautifully cloud- 
ed, than those of any other 
species, and as they lie in what is 
caUed an imbricated form — that 
is, one over ^.he other like the 
tiles of a house, so that at least 
one-third of each envelops the 
one behind it — they are much 
larger in comparison with the size of the individual. In their preparation the scales or plates 
are, in the first place, separated by the application of heat ; they are thus sold to the manufac- 
turers 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 to- 
gether by means of their own substance reduced to poAvder. 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 be- 
tween 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 beveled 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 ; 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. 
Ko 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 while they are exposed to^ 
the heat of boiling water, are formed into plates of any thickness which may be required. 
This species is found in the tropical seas, and occasionally strays into the Mediterranean ; it 
is also common in the Gulf of Mexico. Those which produce the finest shell are taken in the 
waters of the Indian Archipelago. 
The LoGGERPiEAD Turtle, G. caretta, is the largest of the genus, sometimes weighing eleven 
