780 MAMMALIA. 
number, are clawed, and the animals walk in plantigrade 
or semi-plantigrade fashion. In most, the mamme are 
thoracic or abdominal. 
The cranial cavity is small; the skull is never high; the 
facial region is long; the zygomatic arch is slender or 
incomplete. Except in Potamogale, there are clavicles. 
There are never fewer than two pairs of lower incisors. 
The enamelled molars have tuberculated crowns and well- 
developed roots. In many cases it is not easy to distinguish 
the usual division of the teeth into incisors, canines, pre- 
molars, and Bee but in many the dentition is typical— 
4,154 3= 
In the hedgehog, according to Leche, i. 3, pm. 2, m. 1-3, 
of the upper jaw, and i. 3, c., pm. 3, m. 1-3, of the lower 
jaw, are persistent milk-teeth, but, according to others, the 
milk-teeth are represented by mere rudiments (“ prelacteal 
germs”), and the functional teeth correspond to the perma- 
nent set of other mammals. 
The cerebral hemispheres are smooth, and leave the 
cerebellum (and sometimes the corpora quadrigemina) 
uncovered; the olfactory lobes are large; the corpus 
callosum is short and thin. Thus, as regards the brain, | 
the Insectivora represent a low grade of organisation. 
The stomach is a simple sac; the intestine is long and 
simple, but the vegetarian forms have a cecum. In most 
there are odoriferous glands, axillary in shrews, but usually 
near the anus. 
The testes are inguinal or in the groin, or near the 
kidneys, not in a scrotum. The penis may be pendent 
from the wall of the abdomen, but is usually retractile. 
There is a bicornuate uterus. Several and usually many 
offspring are born at once. 
The allantoic placenta is discoidal and deciduate. There 
is a provisional yolk-sac placenta. 
Insectivora are represented in the temperate and tropical 
zones of both hemispheres, but not in S. America (except 
in the Northern Andes) nor Australia. In the former 
continent their place is taken by the insectivorous opossums. 
Examples.—The hedgehogs (Zr¢maceus), throughout Europe, Africa, 
and most of Asia, dentition ree the shrews (Sorex), in 
