482 LEON AUGUSTUS HAUSMAN 
The cuticular scales of the hairs and spines. The finest of the 
hairs—the wavy hairs from the auricular depression (fig. 43, A 
and #), dorsum (fig. 43, G), and venter (fig. 48, 1)—bear the larg- 
est cuticular scales (fig. 87), and as we pass in our examination 
from the wavy hair to the thicker, stiffer, straighter type (the 
type here called the flattened spiny hair), we find that the scales 
decrease in size; their edges become more closely set together. 
The greater the thickness of the spiny flattened hair (and the 
consequently greater spinosity), the smaller, relatively, and the 
more irregular in ectal outline are the cuticular scales. 
This alteration in the form of the scales is illustrated by the 
three types of the spiny flattened hair, each one, in the order 
given, being thicker and consequently a trifle more stiff and spi- 
nous than its predecessor. These types are: the spiny flattened 
hair of the dorsum (fig. 58), the short spiny flattened hair of the 
top of the head (fig. 64), and the long spiny flattened hair of the 
venter (fig. 67). A comparison of the figures referred to. will 
make clear the relations of the scales. It will be noted that the 
larger and stiffer and more spinous the hair becomes, the smaller, 
relatively, are the cuticular scales and the more closely are their 
ectal edges crowded together. 
As the transition from the spiny hairs to the true spines pro- 
gresses, so also does the decrease in the relative sizes and irregu- 
larity of the scales, until upon the surface of the true spines, such 
as the largest of those found upon the dorsum, the scales are so 
closely massed together as to render the tracing of their indi- 
vidual edges extremely difficult. ‘these can be seen only near 
the base of the spine; higher up the attrition, to which so stiff an 
appendage as a rigid, immobile spine is subjected, leaving the 
surface smoothly polished and obliterating all traces of the edges 
of the scales. 
The medulla of the hairs and spines. The medulla likewise 
shows regular transitional forms between the wavy hairs and 
the spines. In the fine wavy hairs it is to be found only as 
streaks of minute, isolated cell fragments in various portions of 
the hair shaft, which, as has been indicated in the discussion of the 
hairs of the mammals in general, may denote that this type of 
