and on Scales in Mammals. 5 



are always wanting upon these scales, but they appear behind 

 and sometimes also between them. Where the scales are 

 well developed slight development of the hair is usually 

 noticeable. This is especially striking in the case of so-called 

 naked tails. Naked indeed they are not, e.g. the tails of rats 

 and mice, but the quadrangular scales are here arranged in 

 rings. Behind each scale project the hairs, which accordingly 

 assume a verticillate arrangement. In other forms [Didelphi/Sj 

 MyrmecojjJiaga tamandua) the scales are imbricated and the 

 scanty hairs appear behind them. These different conditions 

 led me to the important conclusion that the scales are the 

 primary structures and that the arrangement of the hairs is 

 due to them. This proposition is literally confirmed by 

 Romer *, in his recently-published investigations upon the 

 armature of the armadillos. The author referred to found 

 this armature — apart from the ossification which subsequently 

 sets in — to be composed of scales, " to which he attaches the 

 morphological value of a scale in the sense of the scales of 

 Reptiles." 



My earlier investigations led me to conclude that in former 

 times Mammals in general were provided with a coat of scales 

 which in the case of Manis, albeit in a peculiarly specialized 

 manner, still extends over the entire body, so far as it is 

 turned towards the light. Elsewhere, on the contrary, I 

 found it still persisting upon the tail alone. This point 

 naturally attracted attention, and to a certain extent the 

 following explanation seemed to suggest itself : — The tail, as 

 a terminal structure of the body which has in many cases not 

 undergone specialization, might have preserved more primitive 

 conditions in its integument than the trunk. For the trunk 

 a thick coat of hair was of importance, if only to preserve the 

 animal heat. A hairy coat of this kind naturally came into 

 conflict with the covering of scales, as to which proofs will be 

 furnished later. 



In spite of this, my hypothesis here exhibited its weak 

 side t« Hence it was inevitable that there should arise, to a 

 certain extent of itself, the question whether there are still 

 found in the case of other Mammals, and also in other places, 

 indications of a coat of scales, or at least indications of the 

 previous existence of such a coat. 



* Roiner, Jenaische Zeitschr. f. Naturw. Bd. xxvii., 1893, p. 543. 



•j- This was, moreover, not entirely disposed of by the observation made 

 in the meantime by von Jontink (in ]\Iux ^^'eber'9 ' Zoologische Ergeb- 

 nisse einer Reise in Niederliind. Ost-lndien,' Bd. iii. p. 81), that also in 

 the case of mice scales appear upon the extremities, — an observation 

 which was extended by de Meijere [1. i. c.) to numerous Kodentia, to 

 Dasypodidae, and especially to Insectivora. 



