438 THE ZOOLOGIST. 



EDITOKIAL GLEANINGS. 



In the ' Quarterly Journal of Microscopical Science,' Dr. W. G. 

 Eidewood has published a most valuable paper " On the Structure of 

 the Hairs of Mylodon listed, and other South American Edentata." We 

 are glad to see that Dr. Ridewood is dissatisfied with the present com- 

 position of the order Edentata, which, as he remarks, will probably 

 prove to be an unnatural assemblage of animals, and that, acting on 

 further knowledge, it will probably prove necessary to remove the Old 

 World forms Manis and Orycterojms to constitute two new orders by 

 themselves. The diagnoses of hair- structure given in this communi- 

 cation are of too technical a nature for reproduction in our pages ; but 

 the publication has prompted a paper by Mr. R. Lydekker in ' Know- 

 ledge ' on "Plant-bearing Hair," of which we cannot do better than 

 give the following abstract : — 



The author remarks that, " apart from its extremely coarse and 

 brittle nature, the most striking peculiarity of the outer hair of the 

 Sloths is its more or less decidedly green tinge. . . . Now green is a 

 very rare colour among mammals, and there ought therefore to be 

 some special reason for its development in the Sloths. And, as a 

 matter of fact, the means by which this coloration is produced is one 

 of the most marvellous phenomena in the whole animal kingdom — so 

 marvellous, indeed, that it is at first almost impossible to believe that 

 it is true. The object of this peculiar type of coloration is, of course, 

 to assimilate the animal to its leafy surroundings, and thus to render 

 it as inconspicuous as possible ; and, when hanging in its usual posi- 

 tion from the under side of a bough, its long, coarse, and green-tinged 

 hair is stated to render the Sloth almost indistinguishable from the 

 bunches of grey -green lichens among which it dwells. In the outer 

 sheath of the hairs of the ai there are a number of transverse cracks, 

 and in these cracks grows a primitive type of plant, namely, a one- 

 celled alga. In the moist tropical forests forming the home of the 

 Sloths the algae in the cracks of their hair grow readily, and thus com- 

 municate to the entire coat that general green tint which, as already 

 said, is reported to render them almost indistinguishable from the 

 clusters of lichen among which they hang suspended." 



Mr. Lydekker adds some weighty remarks in his paper. " It is 

 quite clear that an alga would have been of no advantage to the Sloths 



