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tely imbricated, there is always and constantly to find placed between 

 every two scales a long stiff hair flanked by the two short hairs. Where 

 the scales are black, there the stiff hairs too are black, where the for- 

 mer are yellow, there the latter too are yellow. The yellow distal part 

 of the tail measures about 150 Mm., that is also 3 / 7 of its whole length 

 — in Uromys macropus the tail is yellow for 2 / 3 of its length. 



I discussed the covering of the tail somewhat in extenso, because 

 this point seems nearly always to have been overlooked as insignifi- 

 cant, — at least this organ has been always described as being more 

 or less hairy or naked *) a. s. o. — and more especially as Professor Max 

 Weber has brought this matter in discussion ; see his paper entitled 

 „Beiträge zur Anatomie und Entwicklung des Genus Manis" in „Zoo- 

 logische Ergebnisse", 1891, zweiter Band, Erstes Heft. 



There is an endless variation in size and shape of the scales of the 

 tails among the different Mice- species, as well as in the form of their 

 margin, but very constant seems to be the above described arrange- 

 ment of the three hairs with respect to the scales. The mentioned 

 hairs may be shorter or longer, so that the tail looks more or less 

 hairy , probably 2 ) it will appear that this does not depend on the 

 number of the hairs which (perhaps) always and constantly is equal to 

 three times the number of scales. It seems to me that I detected here 

 a highly important and interesting law of nature of a very far rea- 

 ching significance. Horsfield has paid more attention to the arrange- 

 ment of the hairs of the tail than all later authors did together, at 

 least he was on the point to detect the above explained law, as he 

 wrote in 1824 (Zoological researches in Java) à propos Mus setifer: 

 „the tail is more naked than that of the Mus decumanus ; a few short 

 „delicate hairs arise, in very small tufts of two or three, 3 ) from the 

 „scales composing the rings." 



Above I remarked that in M. armandvillei there are on hands and 

 feet short stiff hairs placed in very regular parallel rows; well then, 

 although true scales are absent the underlying tabulated skin is very 

 good developed and here again the hairs generally are arranged in 

 distinctly separate groups of three, rising from the distal margin ot 



1) As far as I am aware there are no Mice with a naked tail. 



2) I say „probably" as I had no time to examine all the different species, but I saw 

 it in every specimen that I examined, in specimens belonging to Hesperomys-species too. 



3) I italicize, 



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