TORTOISES AND TURTLES. 387 



and formed a valuable food supply for the crews of ships. Some of these 

 tortoises are remarkable for the extreme tenuity and relatively small size of 

 the shell, which is but little stouter than leather, and can be easily pierced 

 with a knife. This is very notably the case with T. ephippium of the 

 Galapagos Islands, fine examples of which are now preserved in the British 

 Museum. Some of these monsters measure over four feet along the curve of 

 the shell, and have been known to yield close upon four hundred pounds weiglit 

 of excellent meat. In the Galapagos Islands these tortoises make regular 

 tracks to their drinking-places in the hills, and feed chiefly upon the 

 succulent stems of the cacti, so common there. During the breeding season, 

 the males, according to Darwin's well-known account, utter a loud roar, 

 audible at a great distance. The ordinary tortoises of South Europe, Algeria, 

 and Egypt, frequent dry sandy localities, where they have full opportunity 

 of basking in the rays of the sun. In Europe, at least, they hibernate during 

 the cold season, by burying themselves deep in the earth, reappearing with 

 the returning warmth of sjjring. In addition to their normal vegetable food, 

 these tortoises are not averse to an occasional snail or insect. Four peculiar 

 tortoises from South Africa are referred to the distinct genus Humopiis, on 

 account of the fore part of the palate lacking the disfmct mediari ridgo, 

 characteristic of all the species of Testudo. Moreover, the neural bones of 

 the carapace are never alternately quadrangular and octagonal, but always 

 irregularly hexagonal, with the shorter of the two lateral surfaces at the hind 

 end. The typical H. areolatus has but four toes on the front foot, whereas 

 in another species there are five. 



The three species of hinged tortoises from Tropical Africa, forming the 

 genus C'miocys, are easily and broadly distinguished by the presence of a 

 ligamentous hinge across the hinder third of the carapace, by means of which 

 the posterior opening of the shell can be completely closed. These tortoises 

 are small reptiles, not exceeding some nine inches in length ; and in habits 

 the majority are amphibious, thus connecting the land tortoises with the 

 terrapins. Madagascar is the sole habitat of a single peculiar tortoise {Pyxis 

 arachnoides), distinguished by having the front part of the plastron articulated 

 to the remainder by a transverse hinge. In this species, therefore, the front 

 aperture of the shell is capable of being closed at the will of its owner. 



Coming to the terrapins, we find that these are distinguished from the fore- 

 going by the toes being either webbed, or having rudiments of such webbing, 

 as well as by the presence of three (instead of two) joints in the middle toe 

 of both the front and hind-foot. In the fore-foot the metacarpal bones are 

 also much longer and more slender than in the preceding group. Foremost 

 among these come three small Oriental genera, respectively known as 

 Geoemyda, Nicoria, and Cyclemys, all of which difler from those which follow 

 by having the shorter lateral surface of the hexagonal neural bones of the 

 carapace placed at the hinder end — a feature in which they agree with 

 llomopus. Of these forms it will suffice to mention that the species of 

 Cyclemys differ from the others in having the hinder half of the plastron 

 movably articulated by means of a transverse bony hinge, in consequence of 

 which they are commonly spoken of as hinged terrapins. 



In all the other members of the family, the hexagonal neural bones of the 

 carapace have the shorter of the two lateral surfaces on each side situated in 

 front. It is unfortunate that this important characteristic is Ixidden from 

 view by the superficial bony shields — unless in the rare instances where they 

 are suificiently tran.oparent to allow of the underlying bones being seen 



