56 



ERINACEID.E— ERINACEUS 



varies greatly in size at different seasons of the year. It is most 

 voluminous in October, and at that time equals about 3-04 per cent, of 

 the animal's total weight. During the early part of hibernation it 

 rapidly diminishes, and at the beginning of January is only about 1-5 

 per cent, of the total weight, or, allowing for loss of weight by the whole 

 animal, only -33 of its own original weight. By the end of March it is 

 only -9 per cent, of the total weight ; and, continuing to atrophy, is by 

 June reduced to a few fibrous cords. Thenceforward it increases until 

 the commencement of the next hibernation. 



This gland probably acts as a storehouse for fat, which accumulates 

 in it so long as the animal feeds. During hibernation it gives up the 

 fat and probably becomes transformed, a few cells at a time, into highly 

 nutritive matter, fat alone being not sufficient to sustain life. 



DIMENSIONS IN MILLIMETRES:— 



* Measured by T. V. Sherrin, to whom I am indebted for particulars. 



The table suggests that males are larger than females ; see also 

 the weights given below. 



Skull: — Greatest length, 55 to 57 ; basal length in middle line, 53 to 

 57 ; palatal length in middle line, 42 to 43 ; length of upper tooth- 

 series, 28 to 29 ; same in lower jaw, to tip of incisor, 26 ; greatest breadth 



