CLASS III. REPTILIA: ORDER 1. CUELOXIA. 



350 



THE IMBRICATED TURTLE AT SEA. 



" Each turtle has 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 IIawk's-Bill Turtle, 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 funiislies the 

 w ell-known Tortoise- Shell of commerce, it is much sought after. Although the greater number 



of the whole order of Chelonia 

 have the back and sternum cov- 

 ered with horny plates or scales, 

 it is almost exclusively those of 

 the present species whicli are 

 applicable to the purposes of 

 art. The thirteen plates with 

 which the whole upper part of 

 the shell is covered, are in feet 

 mucli thicker and stronger, as 

 well as more beautifully cloud- 

 ed, than those of any other 

 species, and as they lie in what is 

 called an inihricatrd form — that 

 is, one over the 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 tlieir preparation the scales or plates 

 are, in the first place, separated by tlie 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 tlie sul)stance 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 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 eff"ected bj- 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 w'ay, 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 

 foUow^ing 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 Avater ; 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 powxler 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 ]\Iediterranean ; 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 Loggerhead Turtle, C. caretta^ is tlie largest of the genus, sometimes weighing eleven 



