CHAPTER XII. 



THE INSECTIVORES, Order INSECTIVORA. 



THE absence of any vernacular name for that group of Mammals, of which the 

 shrews, moles, and hedgehogs are the best known representatives, compels us to 

 adopt an anglicised form of the Latin term by which the group is known; 

 and we accordingly use the term Insectivores in this sense. This term, it is almost 

 superfluous to add, refers to the insect-eating habits of most of the members of 

 this order, and it is a good one, since, with the exception of the bats, there is no 

 other group of Mammals which prey so exclusively on insects, or other small 

 creatures. 



Most of the Insectivores are comparatively small-sized animals ; and, with the 

 exception of the family of tree-shrews, and some of the aquatic forms, all are of 

 more or less purely nocturnal habits. In the absence of any very strongly-marked 

 characteristics, like the wings of the bats, the group is by no means easy of strict 

 definition, more especially when we have to avoid entering into the consideration 

 of abstruse anatomical details. 



In addition to their generally small size and nocturnal habits, the 

 CHaracteristics. . . . . 



Insectivores may immediately be recognised by the following struc- 

 tural features. All their toes are furnished with claws, and are in most cases five 

 in number on each foot ; w-hile in no instance is either the thumb or the great toe 

 capable of being opposed to the other digits. They walk either on the whole, or 

 the greater portion, of the soles of their feet ; and never on their toes only, in the 

 manner of a cat or dog. Their upper molar teeth carry a number of small and 

 sharp cusps, w r hich are arranged either in a V-shaped or a W-shaped pattern ; and 

 their incisor teeth, of which there are not less than two pairs in the lower jaw, 

 never assume the chisel-like form found in all the Kodents (rats, porcupines, 

 hares, etc.) ; but the first or innermost pair is very frequently larger than either 

 of the others, thereby distinguishing them from the Carnivores. In no instance 

 is one pair of the cheek-teeth in each jaw ever modified so as to act with 

 the scissor - like action characteristic of so many of the Carnivores. Then 

 again the tusks, or canine teeth, are generally not markedly distinct from the 

 other teeth, 1 so that it is frequently a matter of some difficulty especially in the 

 lower jaw to decide which teeth are incisors, which tusks, and wrhich premolars. 

 This may be readily verified by comparing the skull of a hedgehog with that of 

 a dog, in which the tusks cannot possibly be confused either with the incisors in 

 front, or with the premolars behind. 



If, again, we examine the skeleton of an Insectivore, it will be found that 

 there are (with the single exception of one peculiar African species) always a pair 



1 This is not so in the common tenrec, which has large tusks. . 



