360 MAMMALIA OF INDIA. 
take it alive. As yet nothing is known of its habits. Of the last family, 
Caviide, the cavy and the capybara are well known to travellers in 
South America, and the common guinea pig is familiar to us-all. 
FAMILY HYSTRICIDA—THE PORCUPINES. 
In this family the hairs of the body are more or less converted into 
spines or quills ; the form of the skull is peculiar, being ovate, often 
greatly inflated with air cavities in the bones ; the facial portion is broad 
and short; the malar portion of the zygomatic arch has no inferior 
angular process as in the Octo- 
dontide ; the occipital plane or 
hinder-surface is perpendicular, 
with a median ridge; the in- 
cisor teeth are large and power- 
ful; the molars with external 
and internal folds, four in each 
jaw. The form is robust ; imbs 
sub-equal ; fore-feet with four 
toes, and a small wart-like 
thumb ; hind-feet with four and 
five toes; tail long in some, 
short in others. There are two 
sub-families,—Sp/ingurine and 
Skull of Porcupine. fTystricine. With the genera 
of the first we have nothing to 
do. They include the prehensile-tailed porcupines of South America, 
Sphingurus prehensilis, S, villosus, and S. ALexicanus, all arboreal forms, 
and the Canada porcupine (£7ythizon dorsatus) which is covered with 
woolly hairs and spines intermixed. The true porcupines, sub-family 
fTystricine, consist of two genera, both of which are represented in 
India—Atherura and Hystrix. 
SUB-FAMILY HYSTRICIN4A—THE TRUE PORCUPINES. 
Grinding teeth semi-rooted ; skull rather more elongate ; infra-orbital 
foramen of great size ; clavicles imperfect, attached to the sternum, and 
not to the scapula; upper lip furrowed; tail not prehensile; soles of 
feet smooth. The female has six mamme. In these points they differ 
from the American arboreal porcupines (Sphingurus), the skull of which 
is very short, the tail prehensile, the soles of the feet tuberculated, and © 
the female has only four mamme. 
