known to weigh from fifteen to sixteen hundred pounds,--while others, whose carapaces measured more than fifteen feet in circumference and seven feet in length, exceeded eighteen hundred pounds. Marine Tortoises are met with in herds more or less numerous in all seas, principally towards the torrid zone in the tropical regions, on the shores of the Antilles, in Cuba, Jamaica, St. Domingo, the Gulf of Mexico, and in the Indian Ocean. Those occasionally found by navigators in the North Atlantic and Mediterranean seem to be wanderers separated from some travelling bands. [Illustration: Fig. 40.--Green Turtle (_Chelonia Mydas_).] Of all reptiles, the Sea Tortoise is the most useful to man. In countries where they are common, and where they attain an enormous size, their flesh is the most healthy and nourishing food, and their carapace serves as a canoe in which the natives paddle along the shores. They even roof their huts with them; they convert them into drinking-troughs for their cattle and into baths for their children. According to Strabo and Pliny, the ancient inhabitants of the shores of the Indian Ocean and the Red Sea converted the enormous carapaces of the Tortoise which frequented their shores into coverings for their houses, and boats for paddling along the coast. The fat of many species, when fresh, is used as a substitute for oil and butter. When the musk-like odour of this fatty substance, as in _Chelonia caouana_ and _C. caretta_, becomes too repulsive for food, it is employed in embrocations, in tanning leather, or in lamps. The eggs of nearly all the Turtles are sought after for their flavour. Finally, the carapace of several species constitutes a valuable material much employed in the arts, and known as tortoise-shell. This material is sought after in consequence of its hardness and the fine polish of which it is susceptible, and also for the facility with which it is worked. It has a strong resemblance to horn, but is easily distinguished from it. Though, like horn, it is formed of parallel fibres, it seems to be rather the result of exudation, consisting of a kind of solidified mucus. Its texture is homogeneous; it can be cut and polished with precision and beauty; in short, under the influence of a gentle heat, it is softened and can be modelled into any fashion, according to the taste of the moulder; after becoming cool it retains the desired shape. [Illustration: Fig. 41.--Capturing Turtles.]