Protective Resemblance in the Sloths

As “mimicry” and “protective resemblance” have chiefly been noticed among insects and the lowest of vertebrated animals, the following observation regarding the three-toed sloth, made at the beginning of this century, and therefore much in advance of the period at which attention had been directed to this subject, is, in these days, not without interest. It is taken from a work not frequently met with, namely, Baron Albert von Sack's “Narrative of a Voyage to Surinam” (London, 1810). In chap. xvi. at p. 170, he says:-“The colour and even the shape of the hair are much in appearance like withered moss, and serve to hide the animal in the trees, but particularly when it gets that orange-coloured spot between the shoulders, and lies close to the tree; it looks then exactly like a piece of branch where the rest has been broken off, by which the hunters are often deceived.” The colour of the hair of the body is thus distributed in Arctopithecus castaneiceps , A. griseus , and A. flaccidus (“Notes on the Species of Bradypodidre in the British Museum,” by the late Dr. J. E. Gray. Proc. Zool. Soc., 1871, p. 428, Plates xxxv.–xxxvii.).