62 



TORTOISES AND TURTLES. 



constitute the last and seventh group of the genus, and are distinguished from all 

 the others by the great prolongation of the anterior extremity of the plastron, which 

 is covered by a single gular shield only. The former attains a length of about 7£ 

 inches, and has an elongated and very convex carapace, of which the hinder margin 

 is at most but slightly serrated. In colour, the shell is yellow above, each shield 

 being bordered with black, and usually ornamented with a black spot in the 

 centre ; while the plastron is black in the middle, or has some large black blotches. 

 Areoiated Nearly related to the true tortoises, with which it agrees in the 



Tortoise. general structure of its shell, the areoiated tortoise (Homopus areo- 

 latus), of South Africa, together with three other allied species from the same 

 continent, differs by the absence of the median ridge on the front of the palate 

 characterising all the former, and is on this account referred to a distinct genus. 



If the horny shields be stripped 

 from the carapace, it will be 

 found that the underlying neural 

 bones, instead of being alter- 

 nately octagonal and quadran- 

 gular, are irregularly hexagonal, 

 with the shorter of the two 

 lateral surfaces placed posteri- 

 orly ; since, however, the same 

 feature occurs in some of the 

 true tortoises, it is not absolutely 

 characteristic of the genus. The 

 areoiated tortoise is a small 

 species, with a shell of only 4 

 inches in length. It is char- 

 acterised by having only four 

 claws on the front feet, and by 

 its depressed carapace, which is of equal width throughout, and has even margins. 

 On the back, the shields are more or less inflated, and separated from one another 

 by deep channels ; the centre of each shield having a depressed areola, surrounded 

 by concentric grooves. In colour, the carapace is olive, with a reddish brown 

 centre to each shield ; while the plastron is brown in the middle, and yellow at 

 the edges. A second species (H. femoralis) differs by having the hinder margin of 

 the shell serrated, and a conical tubercle on the hinder surface of the thigh ; 

 while in a third (H. signatus), there are five toes on each fore-foot. Lastly, H. 

 nogueyi differs from all the others in its vaulted carapace, which is gibbose behind ; 

 this species being from Senegal, while the other three are South African. In 

 general habits it is probable that the members of this genus closely resemble the 

 true tortoises. 



Three remarkable tortoises inhabiting tropical Africa constitute 

 a genus distinguished at a glance from the other members of this 

 section of the family by the circumstance that the hinder portion of the carapace 

 is articulated to the anterior moiety by a ligamentous hinge, upon which it is 

 freely movable, so that when the animal is withdrawn the hinder extremity of 



AKEOLATED TORTOISE. 



Hinged Tortoises. 



