92 THE NEOG^IC REALM. [CHAP. III. 



tioned Nesocerodon and Issiodoromys (p. 89), it seems highly 

 probable that these are really the ancestral forms of the modern 

 Hystricomorpha, although their lower jaws approximate to the 

 general type of those of the more generalised Sciuromorpha and 

 Myomorpha. 



The last section of the order (Lagomorpha), which includes the 

 hares and picas, and is essentially a northern one, is but poorly 

 represented in Neogaea ; the picas (Lagomyidcz) being unknown 

 there, while in the whole of the realm there are only two species of 

 Leporidce, one of which is Brazilian. 



It has been usual in zoological systems to include under the 

 title of Edentata not only the armadillos, anteaters, 

 and sloths of South America, but likewise the Old 

 World pangolins (Manida) and aard-varks (Orycteropodidaz). 

 There can, however, be no doubt that there is little or no 

 connection between the two groups, and the latter may accord- 

 ingly be separated as a distinct order under the title of ErTodientia. 

 In this restricted sense the edentates at the present day are, per- 

 haps, the most characteristic and remarkable of all the Neogaeic 

 mammals. Whereas, however, the sloths and anteaters are 

 entirely Neogseic, a few of the armadillos have wandered at a 

 comparatively modern date as far north as Texas ; but this does 

 not detract from their essentially southern character, seeing that 

 they are well represented in the Santa Cruz beds, and, if we 

 exclude certain remains of doubtful affinity from the Oligocene 

 of France, are quite unknown elsewhere. This, however, is by 

 no means all, since there are two extinct families of the order, 

 dating from the Santa Cruz beds, which were extremely abundant 

 during the Pliocene and Plistocene epochs ; some few of these 

 having managed to obtain an entrance into North America 

 about the Miocene epoch. Central and South America may 

 accordingly be considered as essentially the home of the edentates ; 

 and are thus broadly demarcated from all other parts of the world. 

 It would be superfluous to point out all the distinctive features of 

 the order, but it may be mentioned that none of the living forms 

 have teeth in the front of the jaws ; while in all those genera in 

 which teeth are present, these are of comparatively simple 

 structure, being unprovided with a coating of enamel, growing 



