CHAPTER XVI 



mSECTIVOEA CHIKOPTERA 



Order XI. INSECTIVORA. 



The Insectivora^ are an order of mammals to which it is (to 

 quote Professor Huxley) "exceedingly difficult to give a definition." 

 They are, however, none of them large animals, and most of them 

 are nocturnal in habit — two circumstances which may have had 

 something to do with their survival from past ages, as may have 

 also their modification to so many and diverse modes of life ; 

 for everything points to the antiquity of the group. They are, 

 for instance, more or less plantigrade. The snout is generally 

 long, and is often prolonged into a short proboscis.^ There is 

 a tendency for the teeth to be of a generalised type, and 

 their number is often the typical mammalian forty -four. 

 Moreover, trituberculate teeth, which are certainly an ancient 

 form of tooth; are common ; and indeed the Insectivora of- the 

 southern regions of the globe, e.g. Centetidae, Solenodontidae, and 

 Chrysochloridae, have the most prevalent trituberculism, a fact 

 which is of importance in considering the age of the animal' life 

 of these regions of the world.t The limbs are, as a rule, provided 

 with fi^ie digits. The hemispheres of the brain are usually 

 smooth, and do mit extend over the cerebellum. The palate 

 is often fenestrate as in the Marsupials, and as in that group 

 tlie lower jaw is sometimes inflected. ,But the latter character 

 also occurs in the Sea-lions and elsewhere. Clavicles are present, 

 as a rule, but not in Potamoijidc. ' , 



'See especially Dobson, A Monograph of the Insectivora, London, 1886-90. 

 " Even in the Otter-like Potariiogale tht upper jaw, though broad and flat, 

 projects cunsiderably beyond the lower. 



