are earth- and sand-colored above, and their broad, shelly roof, somewhat 

 counter shaded, extends so far down over the sides as almost wholly to hide 

 the shieldless and more or less hairy under parts, which, in conformity with 

 the common law, are often decidedly paler in color. It is doubtful, though, 

 whether the ventral paleness has in this case much significance beyond the lax 

 and aborted pigmentation of a surface almost never exposed to view. But 

 armadillos' heads and tails are always (?) counter shaded. 



The Myrmecophagidcs, or American Ant-eaters, are all fully furred, and, 

 despite their nocturnal habits, obliteratively colored. Only three species are 

 known, namely, the Great Ant-eater (Myrmecophaga jubata), the middle- 

 sized Tamandua (Tamandua tetradactyla), and the Little Ant-eater (Cyclo- 

 thums didactylus). Myrmecophaga is strictly terrestrial, but does not burrow; 

 Tamandua is chiefly arboreal, and Cyclothurus strictly so, being halfway to 

 the sloths in habits and demeanor. The two larger kinds lack diurnal ob- 

 literative shading, but are equipped with powerful ruptive patterns of black, 

 white and gray.* The exquisite, pale-brown furry coat of the little Cyclo- 

 thurus bears a rather faint obliterative shading, and a blackish ' secant ' stripe 

 along the underside. 



The "Aard-vark" of South Africa (family Orycteropodidcp) represents the 

 only other type of edentate that remains to be considered. It is strictly noc- 

 turnal, fossorial (living in deep burrows), and extremely timid and wary. Its 

 body is scantily clothed with coarse brownish hair, and has in all probability 

 the regular slight 'nocturnal' counter shading. (See the second footnote on 

 page 123.) 



I have already named the general rules which seem to govern these va- 

 rious breaks in the prevalence of full-blown obliterative coloration among 

 mammals. To recapitulate, the exceptions occur, in the first place, among 

 beasts that are habitually or very frequently hidden away from the light, 

 either underground, in caves or hollow trees, in thick vegetation, or in the 

 cloak of night. In the second place, they occur among beasts, mostly non- 



* See Chapter XXII, p. 149. 

 126 



