THE ARMADILLOS. 



183 



Other species, recognizable by a black patch 

 on the back, *have been combined into a 

 separate genus under the name of Arctopi- 

 thecus. 



The Unau or Two-toed Sloth {Cholceptis 

 didactylus), fig. 240, is a native of Guiana and 

 Surinam, and at- 

 tains a greater 

 size than the 

 former species, its 

 total length a- 

 mounting to about 

 28 inches. Its 

 head is thicker 

 than that of the ai, 

 the broad muzzle 

 projects, the neck 

 is short, the body- 

 slender, and the 

 tail is altogether 

 absent. The olive- 

 brown hair with 

 a shimmer of gray 

 is only a little 

 lighter in colour 

 on the ventral sur- 

 face than on the 

 other parts. The 

 hair-covering be- 

 gins at the root of 

 the nose. In both 

 jaws there are 

 strong canines, 

 which are pointed 

 and sharp, and 

 like the cheek-teeth are covered with a layer 

 of black cement. In section they are tri- 

 angular. The upper canines are sharpened 

 to a point by friction against the hinder sur- 

 face, while in the lower ones it is the front 

 that is ground away. The four round cheek- 

 teeth acquire a tranverse ridge by use. The 

 fore-feet have two, the hind ones three claws. 

 The number of the neck vertebrae in the unau 

 is seven (the normal number); in an allied 

 species {Cholcepus Hofmannt) it is only six. 



Fig. 240. — The Unau or Two-toed Sloth {Cholcepus didactylus). 



THE ARMADILLOS 



(DASYPODA). 



This family inhabits the steppes and bushy 

 parts of South America. The skeleton of 



these animals is 

 remarkable for its 

 solidity. The 

 head has the form 

 of a more or less 

 elongated cone, 

 and carries large 

 funnel-shaped 

 pointed ears. Cy- 

 lindrical simple 

 teeth are always 

 present, often 

 even in consi- 

 derable number. 

 Only in the six- 

 banded armadillo 

 does the first of 

 these teeth stand, 

 as already men- 

 tioned, in the pre- 

 maxilla ; in all the 

 others there are 

 only round cheek- 

 teeth, which are 

 sometimes flatten- 

 ed at the sides. 

 They stand at a 

 greater or less 

 distance from one 



another, and get worn away so as to form a 

 transverse median keel. The short tongue 

 is covered with firm horny warts. The zygo- 

 matic arch is complete and semicircular in 

 form, and there is no such downward process 

 as is so characteristic in the sloths. The 

 lower jaw is weak and slim. The neck 

 vertebrae, always seven in number, are often 

 fused together, and the second, the axis 

 vertebra, carries a large and high vertical pro- 

 cess inclined backwards, so that it resembles 



