244 BULLETIN NO. VIL. 
The porcupines (carefully to be distinguished from hedge- 
hogs) constitute a small family of rather large, clumsy and 
indolent rodents which are conspicuous among their fellows 
for the remarkable change which some of the long hairs un- 
dergo. These become altered to form sharp quills which 
usually are so armed with retrorse bristles as to make them 
very perfect defensive weapons. The body is usually heavy 
and low, the head short and blunt with heavy muzzle and 
small ears. The form varies much and, in particular, the tail 
may be short and bristly, or long, naked and prehensile. The 
feet have naked soles and usually have the first digit reduced 
on one or both pairs of limbs. The toes are usually armed 
with very strong curved claws. The eastern porcupines are 
terrestrial, living in burrows or cavities in rocks while on the 
western continent they are more or less arboreal. The food 
consists of roots, fruits, bark, green leaves and pulpy stalks 
and, on occasion, almost anything edible. Like most vegetable 
feeders they are very fond of salt and are as a,result of their 
filthy habits, particularly liable to internal parasites. 
The nasals are frequently very large ; the lachrymal obsoles- 
cent; there is no preorbital process of the temporal as in 
hares ; the zygomas are massive and short. There are four 
molars in each jaw of similar form and size; the incisors are 
large and smooth in front; the palate is excised between the 
molars. Malar bone with no angular process below. There 
are seven cervical, fourteen to sixteen dorsal, five lumbar, 
three or four sacral and from twelve to thirty caudal vertebre. 
The clavicles are poorly developed. There are but four mam- 
mee in the female. 
The porcupines are brought into relation with rodents in 
general by a number of South American animals which com- 
bine the spiny armature with rat-like or hare-like characters. 
The family is very naturally divided into two groups or sub- 
families as well by the diversity in habits as anatomical differ- 
ences of the animals inhabiting the two hemispheres. The Hys- 
tricine, or Old World porcupines, are terrestrial and a number 
of anatomical peculiarities growing out of this habit are obser- 
vable. The Synetherine, or American porcupines, are arboreal 
and thus require more perfect clavicles and ordinarily pre- 
hensile tails. The molars are rooted while the number of toes 
is less, the digits being armed with hooked claws which serve 
in climbing. The soles are tuberculated or roughened. The 
