INSECTIVORA. 723 



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 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 organisa- 

 tion. 



Except in Galeopithecus, the stomach is a simple sac ; the 

 intestine is long and simple, but the vegetarian forms have a 

 cascum. 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 or two-horned uterus. Except in 

 Galeopithecus, 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 nor 

 Australia. In the former continent their place is taken by 

 the insectivorous opossums. 



Sub-order Insectivora Vera. — Insectivores with free limbs suited for 

 movement on land, climbing, burrowing, or swimming. The incisors 

 are of normal form. 



Examples. — The hedgehogs (Erinaceus), throughout Europe, Africa, 



and most of Asia, dentition ^-^ ; the shrews (Sorex), in Europe, 



Asia, and N. America, dentition ^^ . fa e moles ( Talpd), through- 

 out the Palsearctic region ; the tailless tenrec ( Centetes) of Mada- 

 gascar ; the S. African golden moles (Chrysochloris) ; the African 

 jumping shrews [Macroscelides) ; the Oriental tree-shrews [Tupaja). 

 Sub-Order Dermoptera. — Represented by the very divergent Galeopi- 

 thecus, which almost requires an order for itself. The fore- and hind- 

 limbs are connected by a parachute, and the animals can glide from tree 

 to tree, " sometimes traversing a space of seventy yards with a descent 

 of only about one in five." The structure of the incisors is unique 

 among Mammals. They are expanded laterally, compressed from 



