178 EDENTATA 



limited area of distribution, and their small size compared with 

 known ancestral forms, all show that this is an ancient and a waning 

 group, the members of which seem still to hold their own either by 

 the remoteness and seclusion of their dwelling-places, by their 

 remarkable adaptation of structure to special conditions of life, or 

 by aid of the peculiar defensive armature with which they are 

 invested. Their former history can, however, only be thus surmised, 

 rather than read, at present ; for, though we have ample evidence 

 of the abundance and superior magnitude of certain forms in the 

 most recent or Pleistocene geological age, yet Ave have at present 

 no definite evidence as to their origin, or relationship to other 

 orders of mammals. 



The existing members of the order readily group themselves 

 into five distinct families, the limits of which are perfectly clear. 

 These are (1) Bradypodidce, or Sloths; (2) Myrmecophagidce, or Ant- 

 eaters ; (3) Dasypodidce, or Armadillos ; (4) Manidce, Pangolins or 

 Scaly Anteaters ; and (5) Orycteropodiclcc, Aard-varks or African 

 Anteaters. The geographical distribution of these families coincides 

 with their structural distinction, the first three being inhabitants of 

 the New and the last two of the Old World. It has been usual to 

 arrange these families into two large groups or suborders: (1) the 

 Phyllophaga, leaf -eaters, also called Tardigrada, containing the 

 Bradypodidoe alone; and (2) the Entomophaga, insect-eaters, or 

 Vermilingua, containing all the other families, from which some- 

 times the Orycteropodidce are separated as a third suborder under 

 the name of Effbdientia, or Tubulidentata. Such an arrangement 

 is, however, an artificial one, founded on superficial resemblance. 

 The bonds which unite the Manidce to the Myrmecophagidce are 

 mainly to be found in the structure of the mouth, especially the 

 extensile character of the tongue, the great development of the sub- 

 maxillary glands, and the absence of teeth. These characters are 

 exactly analogous to those found in the Echidna among Monotremes, 

 the Woodpeckers among Birds, and the Chamoeleon among Reptiles, 

 — the fact probably being that in countries where Termites and 

 similar insects flourish various distinct forms of vertebrates have 

 become modified in special relation to this abundance of nutritious 

 food, which could only be made available by a peculiar structure of 

 the alimentary organs. A close study of the more essential 

 portions of the anatomy of these animals l leads to the belief 

 that all the American Edentates at present known, however di- 

 versified in form and habits, belong to a common stock. Thus the 

 Bradypodidce, Megatheriidce, and Myrmecophagidce are certainly allied, 

 the modifications seen in the existing families relating only to food 

 and manner of life. The ancestral forms may have been omni- 



1 See Flower, "On the Mutual Affinities of the Animals composing the 

 Order Edentata," Proceedings of the Zoological Society, 1882, p. 358. 



