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 (Dedelphys, 
Myrmecophaga 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 +. Hence it was mevitable 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. 
* Romer, Jenaische Zeitschr. f. Naturw. Bd. xxvii., 1893, p. 543. 
+ This was, moreover, not entirely disposed of by the observation made 
in the meantime by von Jentink (in Max Weber's ‘ Zoologische Ergeb- 
nisse einer Reise in Niederlind. Ost-Indien,’ Bd. iii. p. 81), that also in 
the case of mice scales appear upon the extremities,—an observation 
which was extended by de Meijere (/. 2 ¢.) to numerous Rodentia, to 
Dasypodidee, and especially to Insectivora. 
