160 The Mammalia of Essex : a Contrllnition towards a 



commonest of the order, aiDpearing earlier and retiring later 

 than any other, and it is the sj)ecies most frequently seen 

 by day. It is on the wing in mild seasons nearly up to 

 Christmas, when it finally retires for its winter sleep, 

 choosing almost invariably holes in and about buildings for 

 its home. The flight, unlike that of its larger relative, is 

 low, and well described by its common name, " Flitter 

 Mouse"; the sheltered sides of buildings or hedges being 

 favourite hunting-grounds, no doubt in consequence of its 

 food, gnats and small insects seeking the same protection 

 fi'om the wind. 



Vespertilio Nattereri. Keddish-grey Bat. — This easily 

 distinguished species is reputed to be rare ; in this district, 

 however, it is one of our commonest bats. Houses and 

 buildings are favourite hiding-places in summer ; and in 

 winter, cellars, caverns (as under Colchester Castle), and 

 such i^laces, are generally chosen. Occasionally bats are 

 brought to me late in autumn, drawn up in the buckets of 

 our deepest wells, and three out of four being of this species 

 I have good reasons for beheving that the crevices in the 

 brickwork of the wells are occasionally chosen as hybernacula. 

 I hear the peculiar note of this bat, during its evening flight, 

 more fi-equently than any other in the streets and gardens of 

 Colchester. 



V. Daubentonii. Daubenton's Bat. — This also is not a 

 rare bat in this district. It has one character by which it 

 may be distinguished easily : the wing membrane extends 

 only to the distal extremity of the tibia, leaving the foot 

 free, instead of the membrane being continued to the root of 

 the toes, as is usually the case in other species. Daubenton's 

 bat has been well described as an aquatic species ; its habit 

 of haunting water, either stagnant ponds or running streams, 

 flitting with rapid vibrations of the wings a very few inches 

 from the surface, and apparently spending most of its time 

 of flight there, makes the description " aquatic " a just one. 

 Their usual habitats when at rest are in buildings. In 

 winter I find them, as did Yarrell, under our castle at 

 Colchester. Some that I have endeavoured to keep appeared 



