WATER VOLE. 261 



. number, are deeply grooved externally, and have 

 the crown flattened, whereas those of the genus 

 Mus are tuberculate on the crown, and externally 

 smooth. 



The Brown Water Vole, commonly named the, 

 Water Rat, has the body full, the neck very short, 

 the head short, broad, rounded, and convex above ; 

 the limbs small ; the tail rather long and slender. 

 The snout is small, as are the nostrils, which are 

 lateral, as well as the eyes. The external ears are 

 short, rounded, entirely concealed in the fur, bare 

 internally, unless at the margin, slightly covered 

 externally with extremely soft hairs ; the meatus 

 large, and capable of being exactly closed by a thin 

 angular operculum, having a thickened margin. 

 On the fore foot are five toes, of which the first is 

 very small, the second shorter than the fourth, 

 the third a little longer, the fifth shorter than the 

 second ; the claws extremely compressed ; the sole 

 bare, with papilliform tubercles opposite the first 

 toe, two smaller behind, a fifth between the bases 

 of the third and fourth toes. On the hind feet also 

 are five toes; the first short, the next three of nearly 

 equal length, the middle toe a little longer, the fifth 

 much shorter ; the claws longer and a little stronger ; 

 the sole bare to the tarsal joint, with two tubercles 

 at the root of the first toe, one at the root of the 

 second, another at that of the fifth, and one between 

 the third and fourth. The tail is round, slightly 

 tapering, somewhat compressed towards the tip, and 

 covered with short adpressed hairs. 



