222 



KNOWLEDGE 



[December 1, 1892. 



tlieir own particular modes of life, or that they have not 

 developed special structures unknown among the higher 

 mammals. In truth, precisely the contrary is the ease, 

 since these creatures have taken to modes of life unlike 

 those of the majority of the larger mammals, and have 

 more or less specially modified their structure in accordance 

 with such peculiar habits, so that they are thoroughly and 

 perfectly suited to their environment. And we may add 

 that it is doubtless due to these peculiarities of structure 

 and habits that they have been enabled to survive and 

 hold their own against the competition of the higher forms. 

 Thus, in the first place, with the exception of a few 

 armadillos, the whole of the edentates are strictly noc- 

 turnals ; and while the sloths spend the whole of their 

 lives among the branches of the dense forests of South 

 America, all the others have taken to a burrowing sub- 

 terranean life. Moreover, as we have noticed in an earlier 

 article on " Mail-Clad Animals," the armadillos and the 

 pangolins have acquired a special protection from their 

 foes in the shape of a bony or scaly armour, which 

 is a perfectly unique feature in the whole mammalian 

 class. Another peculiarity of the group is that no less 

 than three distinct sections of its members — namely, the 

 anteaters of South America, the pangolins of Southern 

 Asia and Africa, and the African aard-varks — have taken 

 to feed mainly or exclusively on termites, or so-called 

 white ants. This practice obviously gives them an 

 advantage in the struggle of existence, since, with the 

 exception of the marsupial banded anteater and the egg- 

 laying spiny anteater of Australia (with which, of course, 

 they do not come into competition), no other mammals are 

 in the habit of subsisting exclusively on those insects. And 

 we may notice here that of the three groups of termite- 

 eating edentates, two — namely, the paugolins and the 

 anteaters — are those which have entirely lost their teeth ; 

 while in the aard-varks those organs are retained. As 

 teeth are obviously of no sort of use to animals subsisting 

 on such a diet, we may regard the two former groups as 

 those most specially modified for their particular mode of 

 existence ; and it may thus be suggested that they have 

 taken to termite-eating for a longer period than the aard- 

 varks. A similar observation also applies to the banded 





Fro 2.— Till' Pichieiago. (From .JiU-cliiie.) 



and spiny anteaters of the antipodes, the former retaining 

 a number of minute teeth, while in the latter they have 

 completely disappeared. Needless to say, all termite- 

 eating mammals, whether they be edentates, marsupials, 

 or egg-layers, have extremely long, narrow, and extensile 

 tongues with which to pick up their insect-food ; but the 

 presence of such an organ does not, of course, imply any 

 mutual affinities between the pos3essors thereof, and is 

 merely an instance of the similarity of organs arising from 

 adaptation to a similar mode of existence. The tongue of 

 the aard-varks is, however, far less elongated and exten- 

 sile than that of the pangolins and true anteaters; and, 

 tlierel'ore, tends to conMrm our suggestion as to the relative 

 duration of time since the ancestors of these creatures 

 severally took to termite-eating. Another instance of adap- 

 tation displayed by all the edentates, except the arboreal 

 sloths, is to be found in the pow'erful and generally elongated 

 claws or nails with which tlieir feet are armed, such claws 

 being obviously necessary for a fossorial subterranean 

 existence. Tjje aard-varks, as will be seen from our 

 third figure, have, however, much shorter and blunter 

 claws than any other member of the group; and this leads 

 me to hazard the suggestion that, in addition to having 

 taken at a comparatively late period to termite-eating, 

 these animals have not been accustomed to a subterranean 

 life for so long a time as their reputed kindred. 



Having said thus much as to edentates in general, we 

 must turn to the special consideration of the creatures 

 whose names form the title of this article. 



The armadillos, as their name (a Spanish one) imjilies, 

 are distinguished by the solid armour with whicli their 

 heads and backs are protected ; and it is doubtless the 

 peculiar appearance presented by these animals to which 

 we owe the expression " hog-in-armour." In all the 

 armadillo family the armour takes the form of a series of 

 thicker or thinner bony plates embedded in the skin 

 covering the head and back, and overlain by horny scales; 

 while the under parts of the body and limbs are hairy, and 

 in many species a larger or smaller number of stift' hairs 

 protrude from between the joints of the armour. This bony 

 armour is a perfectly imique feature among existing 

 mammals ; and since each plate is ornamented with a 



more or less ela- 

 borate sculptured 

 pattern, such 

 armour when 

 cleaned by macera- 

 tion forms a most 

 beautiful object. In 

 the true armadillos, 

 as the one repre- 

 sented in Fig. 1, 

 the shield of armour 

 covering the head is 

 quite distinct from 

 that of the body ; 

 while the latter is 

 ~- , divided into three 

 distinct portions, 

 namely, a large 

 solid shield cover- 

 ing the fore-quar- 

 ters, and separated 

 by a larger or 

 smaller number of 

 free movable bands 

 occupying the 

 middle of the 

 body from a nearly 



