18 VERTEBRATA. REPTILIA. 



tiful substance called tortoise-shell is obtained, no 

 other species being available for this purpose. By 

 immersion in boiling water the plates become quite 

 soft, and being subjected to pressure, are made 

 perfectly flat; two pieces are even soldered toge- 

 ther by the same process so completely as to shew 

 no line of union, and even the scrapings and filings, 

 with any small pieces that may be cut away, being 

 softened by heat and placed in metallic moulds, are 

 pressed into any required form at pleasure.* The 

 use of this substance was known to the ancients, 

 by whom it was highly prized. The species is 

 less than the Green Turtle, but inhabits the same 

 seas : its flesh is disagreeable and unwholesome. 



The Loggerhead (C. Caretta) is the largest of 

 the genus, attaining the enormous size of eight or 

 nine feet, and the weight of fifteen hundred pounds. 

 It is of no value for its flesh or shell, but it affords 

 a considerable quantity of oil for lamps. It is a 

 dangerous animal, from its courage and ferocity. 



A species of scarcely less dimensions, though a 

 native of the Mediterranean, has occasionally strayed 

 to our own shores ; its body is covered with a 

 tough leathery skin, without scales or plates. It 

 is the Leathery Turtle (C. Coriacea). The first 

 lyre is reported to have been formed of its shell. 



* Dumeril et Bibron. 



