THE SEROTINE 



133 



that species. The third metacarpal is slightly shorter than in noctula, 

 and is slightly longer than the fifth ; the latter is relatively much longer 

 than its forearm. The foot (both actually and relatively) is smaller, 

 and the longest digit shorter. The tail projects markedly from the 

 interfemoral membrane, the last two vertebrse being free. The thumb 

 is longer, and more slender. The total expanse is actually about the 

 same as in N. noctula, but is less relatively to the forearm length. 



The fur is soft and longer than in Nyctalus, but on the upper sur- 

 face extends on to the wing to a lesser degree ; beneath, the wing is 

 sprinkled with fine hairs, and on the interfemoral membrane these are 

 restricted to an almost invisible scattering on the transverse dotted 

 lines. As in N. noctula, a band of hair may extend from behind the 

 forearm to the carpus, but it is usually much less conspicuous. 



The colour above is dark, varying 

 between " clove " and " Prouts," or 

 " mummy brown " ; many of the hair 

 tips are of tawny shades. The under 

 side affects some tint of " broccoli " 

 brown, often inclining to tawny. The 

 line of demarcation is sometimes mode- 

 rately distinct, following the wing, and 

 thence running forward beneath the ear 

 to the mouth. The sparsely haired 

 portions of the face are deeply pig- 

 mented, as are the wing, interfemoral 

 membrane, limbs, and ear. 



Bell states that the juvenile colours 

 are more obscure, and Ruskin Butterfield 

 writes me that the undersides of old 

 specimens are conspicuously darker, 

 but it is not known whether there is 

 any seasonal colour change or mciilt. 

 A very dark female in good condition, 

 shot by Ogilvie-Grant at Yalding, Kent, 

 on 23rd May, suggests that there may 

 be, as in so many bats, two phases, a 

 melanic and a brown, and seems to be 

 contrary to Bell's statement that "the 

 female is much brighter than the male." ^ 



In the teeth (Fig. 12) the inner upper incisor is long, strong, and 

 bifid, until worn down : its length is at least double that of the small 



^ A similar sexual coloration is, however, present in Miniopterus dasythrix 

 (Temminck) and M. fraterculiis of Thomas and Schwann (see Proc. Zool. Soc. 

 (London), 20th Feb. 1906, 161 -162). 



Fig. 12. — Front View of Incisors 

 AND Canines of Vespertilio serotinus 

 (enlarged and diagrammatic). 



N 2 



