VII A WOODLAND CODGER 203 
including many rat-like animals, small and large, 
some belonging to North Africa, but mostly South 
American. 
In many members of this group the hair has a 
peculiar sharpness, with more or less intermixture 
of stiff prickly hairs, becoming quills in the most 
typical ; while others, as the chinchilla and coypu, 
are noted for the extreme softness of their fur, 
making it valuable in trade. 
The central family is that of the porcupines 
(Hystricidz), long ago divided into two branches: 
—— the synetherine, or New World arboreal porcu- 
pines, and the hystricinine, or Old World terres- 
trial porcupines; but this division is made on 
anatomical grounds, not upon difference of habitat 
or habits, to which the classifiers are more blind 
than is always well for the stability of their work. 
To the former branch belong our subject and its 
South American cousins, the tree-porcupines; to the 
latter, the common European porcupine. 
Of the last named (Aystrix cristata) a brief 
account by W. S. Dallas may be useful for pur- 
poses of comparison with the characteristics of the 
American form. 
“The head, shoulders, limbs, and under parts 
are clothed with short spines intermixed with hairs 
usually of a dusky or brownish black hue; the 
neck is marked with a whitish collar; from the 
back of the head and neck there arises a great 
crest of long bristles, many of them fifteen or six- 
teen inches in length, which can be elevated and 
