NATTERER'S BAT 



i8i 



conceal the small eyes. On the wing it extends above and below 

 about to a line joining the central points of humerus and femur, and 

 is not conspicuous on the interfemoral membrane. The foot is ciliated 

 with dusky hairs. 



In colour this bat is very distinctly bicolored, being greyish brown 



between '' wood brown " or " isabella " colour, and " drab " — above and 

 whitish below, the bases of the hairs always dusky or dark brown, 

 and the tips grizzled and shining above. The line of demarcation is 

 distinct, and passes approximately from the angle of the mouth to the 

 junction of the wing and body. The membranous parts are dusky. 



In the young the grizzled hair-tips are wanting, and the colour 

 contrast is greater, the upper surface being darker — " mummy brown " 

 almost to " seal brown " — and the lower sur- 

 face a clearer white. The skin of the foetus 

 is dusky (Proger). 



In the skuU (Fig. i6. No. 3, p. 174) the 

 profile resembles that of M. mystacinus, but 

 the brain-case is far more prominently raised 

 above the face-line and more rounded. 



In the teeth (Fig. 16, No. 3, p. 174, and 

 Fig. 18) the middle upper premolar (there is 

 some variation) is usually about half the size 

 of the anterior, but sometimes almost equals 

 it in diameter and length. 



Geographical variation has not been 

 studied, except in the sub-species M. n, 

 bombinus of Japan, which is stated to be 

 characterised by more abrupt and consider- 

 able inflation of the frontal region of the 

 skull and by darker colour. 



Dimensions in millimetres (see following 

 page). 



Proportionate lengths : — Foot, without claws, about -48 of lower 

 leg; third metacarpal, about -99 of fifth; lower leg, about -41 of fore- 

 arm, and about -36 of head and body. 



Skull: — Greatest length, 15-5; basal length in middle line, 11-25; 

 palatal length in middle line, 7 ; from posterior border of m^ to anterior 

 border of canine, 6 ; ditto in lower jaw, 6 ; greatest breadth at zygoma, 

 9-5; posterior breadth, 7-5; breadth between orbits, 7; breadth at 

 constriction, 4. 



Distinguishing characteristics: — The light colour, large notched 

 ear, elongated tragus, and particularly the ciliated interfeporal 

 membrane, distinguish this bat absolutely from any other British 

 species. 



Fig. 18. — Front View of 

 Incisors and Canines of 

 Myotis nattereri (enlarged and 

 diagrammatic). 



