ruptive patterns, of a peculiar sort, whose function will be explained in a 

 later chapter. The other animals above named — brown and black bears 

 and Pennant's Martin — are all nocturnal. The bears, furthermore, are too 

 big and powerful to need defensive coloration; though, being partially rapa- 

 cious, they do not wholly lack disguising-patterns. (See Chapter XXII.) 

 Thus only the cases of the Fisher and a few other small carnivorous quad- 

 rupeds of like coloration remain in any degree anomalous, while the facts that 

 such beasts are nocturnal, acrobatic, and deep-forest haunting, go far toward 

 clearing up the difficulty. 



The living members of that strange agglomeration of animals usually 

 grouped by naturalists in the order Edentata, are almost all nocturnal, al- 

 though they show otherwise great diversity of habits. Some are fossorial, 

 some terrestrial; others semi-arboreal; others again, arboreal; and still others 

 ultra-arboreal, being, alone among living mammals, practically incapable of 

 any mode of progression except handing themselves, belly-uppermost, along 

 the undersides of tree-boughs and vines. Of course I refer now to the sloths, 

 Bradypodidce. Their protective coloration is probably mimetic, in part at 

 least, like that of certain bats, already mentioned. To be sure, they are often 

 equipped with a slight inverted counter shading (from darker bellies to lighter 

 backs, as in the case of many of the lepidopterous larvae which feed and rest 

 upside down); and their coloration often inclines also toward the 'ruptive,' 

 based on bold, arbitrary patchiness. But these equipments are irregular 

 and inconstant, and rarely or never would they appear to be of dominant im- 

 portance. On the other hand, many travelers have commented on the mimetic 

 function of sloths' queer, weedy-furred coats, aided by their shapelessness and 

 sluggish habits; and such is very probably their chief protection. Hanging, 

 lumplike, up among the complex, tangled forms of branch and leaf and vine 

 and vegetable parasite, their rotundity perhaps revealed by the insufficiency 

 of their counter shading, and at the same time obscured by their irregular, 

 shaggy coats, they may well be hard to detect as animate forms. For they 

 must look very much like masses of moss, withered air-plants, or other vegetable 



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