INSECTIVORA 613 



and the corpus callosum is short and thin. In the Hedgehogs 

 (Erinacem} 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 Galeopithecus the stomach is a simple, thin-walled sac ; 

 but in some, as in Centetes and allied genera, the pyloric and 

 oesophageal 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 Tupaia, 

 as well as in the Macroscelididce, all of which probably feed in 

 part on vegetable substances, most of the species possess a caecum. 

 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 (Soriddce, Centetidce, Chryso- 

 chlwidce) the penis is capable of being more or less completely 

 retracted within the fold of integument surrounding the anus ; in 

 some (Galeopitheddce, Talpidce) it is pendent in front of the anus ; 

 while in others (Macroscelididce, Erinaceidce, Solenodontidce) it is 

 carried forwards and suspended from the abdominal wall. In the 

 subfamily Centetince 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 Rhynchocyon the 

 uterine cornua are long and open into a short corpus uteri, which 

 in many species (Soriddce, Talpidce, Centetida\ Chrysochloridce) 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 

 Erinaceus, 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 Chrysochloiis 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 



