142 CLASS MAMMALIA. 



to the several species of vespertiliones. The indicating 

 characters of this sub-genus may be given thus : Incisive 

 teeth, four above, six below, nose simple, ear with auricula 

 or tragus. 



We might be tempted to believe after what has now 

 been said, that the sub-genus vespertilio including species so 

 closely approximating to each other, might occasion some 

 difficulty to the naturalist in making a rigorous specific 

 determination. In truth we can but very seldom make use 

 of the consideration of colour, a character to which we are 

 obliged so often to have recourse in zoology, as all these bats 

 are more or less brown or reddish. Nevertheless when we 

 come to examine them attentively, we are astonished to 

 find that they present so many appreciable differences. 

 Their physiognomy varies ad infinitum. Their ears and 

 auriculae are in proportions extremely different in the dif- 

 ferent species. 



This mode of considering them will furnish the characters 

 of each. 



The vespertilio murinus, or common bat, is that species 

 which has been known in Europe from the earliest period. 

 The figures found of this animal in Johnston and Edwards 

 are by no means good. It had been compared with no spe- 

 cies excepting the oreillard or great-eared bat. From that 

 circumstance it derives its name of vespertilio major in 

 Brisson, and its character, " ears smaller than the head," 

 by which description Linnaeus only meant to oppose it to 

 the smaller species, in which the ears are nearly as large 

 as the body. Linnaeus also changed its name of major into 

 that of murinus, in consequence of Brisson's observation 

 that it had hair of a mouse-coloured gray. 



By the following character it may be always recognised. 

 Oblong ears of the length of the head ; auricula shaped 

 like a demi-heart : fur ashy red above, grayish white un- 

 derneath. The murinus has the head moreover tolerably 



