io8 



VESPERTILIONIDyE— PIPISTRELLUS 



hairs are everywhere dusky, the dusky basal portion reaching a length 

 of 7 mm. out of a total of lo mm. on the back. The wing, leg, foot, 

 ear, nose, and naked parts are dusky. The young are generally of a 

 more uniform, usually a darker, colour than the adults, owing to the 

 absence of the grizzled hair-tips, but there are exceptions, as in one 

 labelled 5 th August, which is about the lightest individual which I have 

 seen (see Jenyns ; Fatio; Couch, Zoologist, 1853, 3942). 



Nothing is known of the seasonal changes of this species, but I 

 believe that they resemble those of the genus Nyctalus, since there seems 

 to be a tendency to deeper tints in March and to comparative pallor 



in summer until August. There are cer- 

 tainly no marked changes, and such as 

 occur are obscured by individual variation. 

 Two young ones (Plate II., Fig. 2, 

 p. 16), born in the possession of Whitaker 

 had at birth a few straggling hairs on the 

 muzzle ; the body was dull flesh colour, 

 the wing and ear darker, but lighter than 

 in an adult. One was abnormal in that 

 it neither advanced in size nor apparent 

 development for a month. The other 

 began to grow darker after about five 

 days, and by the twenty-first day the 

 whole body had become dusky. The 

 eyes opened on the eighth day, and about 

 the same time hair began to appear on 

 the back and shoulders, later on the head 

 and chin, lastly on the breast : the belly, 

 however, was still naked on the thirty- 

 third day, when the animal died. 



The skull and teeth are typical of 

 the genus (Figs. 8, No. i, p. loi ; 9, 

 p. 102 ; and 10). 



Individual variation is very frequent, and tends in three directions, 

 i.e., towards melanism, erythrism, and albinism, intermediates of every 

 description being plentiful. One in the Grosvenor Museum, Chester, 

 killed in that city on 6th April 1896, is "coal black, with a rusty 

 tinge on the belly and flanks " (Oldham). Borrer mentions a rusty red 

 one {Zoologist, 1874, 4125), and there is an example of this type in 

 the Royal Scottish Museum at Edinburgh. Of all-white specimens, with 

 or without pink eyes, I know of about seven altogether (see Pelly, Field, 

 14th Sept. 1889, 408, and J. M., Journ. cit., 2nd Oct. 1875, 368; Millais, 

 85 ; and one in Tring Museum). In the most remarkable the wings 

 and ears were white like tissue paper, the legs, arms, digits, nose and 



Fig. 10. — Front View of Incisors 

 AND Canines of Pipistrellus pipi- 

 strellus (enlarged and diagrammatic). 



