7i8 MAMMALIA. 



There are more than two incisors in the mandible. The 

 enamelled molars have tuberculated crowns and well-de- 

 veloped roots. In many cases it is not easy to distinguish 

 the usual division of the teeth into incisors, canines, pre- 

 molars, and molars, but in many the dentition is typical 

 3, i, 4, 3=44- 



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, a mixed and primitive condition. 



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 organisation. 



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

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

 caecum. 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 

 GaleopitkecuS) several offspring and usually many 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. 



Sub-Order Insectivora Vera : Insectivores with free limbs suited for 

 movement on land, climbing, burrowing, or swimming. " The upper 

 and lower incisors are conical, unicuspidate or with basal cusps only, 

 the lower not pectinated." 



Examples : the hedgehogs (Erinaceus], throughout Europe, Africa, 

 3133 



and most of Asia, dentition ; the shrews (Sorex\ in Europe, 



2123 



4 I2 3 



Asia, and N. America, dentition ; the moles (Taipei), 



2013 



throughout the Palaearctic region ; the tailless tenrec ( Centetes) 

 of Madagascar; the S. African golden moles (Chrysochloris}'; 

 the African jumping shrews (Macroscelides) ; the Oriental tree 

 shrews ( Tupaia], 



Sub- Order Dermoptera : represented by the very divergent Galeopi- 

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



