INSECTIVORA 613 
and the corpus callosum is short and thin. In the Hedgehogs 
(Erinaceus) the spinal column ends abruptly opposite the third or 
fourth dorsal vertebra in a slender filament, and the dorsal and 
lumbar nerves, given off in front of this point, are carried back- 
wards in two compressed bundles occupying the suddenly narrowed 
spinal canal as far as the sacrum. 
Owing to the similarity in the character of the food, the truly 
insectivorous species, forming more than nine-tenths of the order, 
present little variety in the structure of their digestive organs. 
Except in Guleopithecus the stomach is a simple, thin-walled sac ; 
but in some, as in Centetes and allied genera, the pyloric and 
cesophageal openings are very close together. The intestinal canal 
has much the same calibre throughout, and varies from three (in 
the Shrews) to twelve times (in the Hedgehogs) the length of the 
head and body. In the arboreal genera, Galeopithecus and Tupaio, 
as well as in the Macroscelidide, all of which probably feed in 
part on vegetable substances, most of the species possess a cecum. 
The liver is deeply divided into lobes, the right and left lateral 
being cut off by deep fissures ; and both the caudate and Spigelian 
lobes being generally well developed. The gall-bladder, which is 
usually large and globular, is placed on the middle of the posterior 
surface of the right central lobe. 
In most of the members of the order (Soricide, Centetide, Chryso- 
chloride) the penis is capable of being more or less completely 
retracted within the fold of integument surrounding the anus; in 
some (Galeopithecid, Tulpide) it is pendent in front of the anus ; 
while in others (Mucroscelidide, Hrinaceide, Solenodontide) it is 
carried forwards and suspended from the abdominal wall. In the 
subfamily Centetine and Chrysochloris the testes lie immediately 
behind the kidneys, but in others more or less within the pelvis. 
During the rutting season they become greatly enlarged, forming 
protrusions in the inguinal region. Except in Lhynchocyon the 
uterine cornua are long and open into a short corpus uteri, which 
in many species (Soricide, Talpide, Centetide, Chrysochloride) is not 
separated from the vagina by a distinct os uteri. With the 
exception of Galeopithecus all Insectivora appear to be multiparous, 
the number of young at a birth varying from two to eight in 
Evrinaceus, and from twelve to twenty in Centetes. The position 
of the mammary glands and the number of the teats vary greatly. 
Thus in Galeopithecus there are two pairs of axillary teats, and in 
Solenodon a single post-inguinal pair ; but in most species they range 
from the thorax to the abdomen, varying from two pairs in Gymnura 
to twelve in Centetes. In Chrysochloris the thoracic and inguinal teats 
are lodged in deep cup-shaped depressions. 
Odoriferous glands exist in many species. In most Shrews 
these glands occur on the sides of the body at a short distance 
