1908. I DR. KNUD AXDERSEN^ ON BATS. 255 



younger and aged individuals ; further, some variation in the 

 development of the supraorbital and infraorbital stripes, partly 

 quite individual, partly dependent on age, and partly on the race 

 to which the individuals belong ; and last, there is a certain 

 colour difference between A . j. parvipes, i/ucatanicus, jamaicensis, 

 and cequatorialis {i. e. the northern races) on one side, A. j. litu- 

 i-atus and imhnaru'in (the southern races) on the other side. It 

 has therefore proved convenient to give the description of the 

 coloration under the following five headings : — dark-coloured 

 individuals ; lighter-coloured individuals ; indication of dorsal 

 stripe and white ear-edgings ; facial stripes ; concluding remarks 

 on the colour. 



Darlc-Goloibred individuals. — Upper side, from the shoulder 

 region backward, dark smoky brown, almost blackish brown, 

 this colour confined to the distal third or fourth of the hairs ; 

 base of hairs slate. On the anterior part of the upper side, from 

 the shoulder region forward, the hair-bases are as a rule dis- 

 tinctly lighter, almost smoke-grey. Under side dark smoke-grey 

 or brownish smoke-grey, with a peculiarly grizzled appearance, 

 owing to the short whitish or greyish-white tips to the hairs. 

 Tips of wings (region of third, or second and third phalanges of 

 third digit) generally light-coloured (whitish or yellowish white). 



This is the extreme of the dark colour-type in fully adult 

 individuals (young, not full-grown individuals are still a shade 

 darker or duller). It occurs in all races, but is especially common, 

 and much more frequently retained (or retained in a slightly 

 lighter shade) throughout the whole life, in the northern 

 than in the southern races ; about 75 p. ct. of the fully adult 

 specimens examined of the northern races are "dark," as against 

 only 25 p. ct. in the southern races. By advancing age (the 

 precise period varying considerably) the colour becomes gi'adually 

 of a somewhat lighter shade, even in those individuals which 

 never assume the proper " light phase " described below. 



Lighter-coloured individuals. — Upper side, from shoulder region 

 backward. Front's brown, base of hairs almost wood-brown. On 

 the shoulder region and neck the Front's brown hair-tips are 

 generally very short or altogether wanting, the wood-brown 

 ground-colour of the fur therefore more or less, or completely, 

 exposed, producing an often very strong conti^ast between the 

 anteiior and posteiior parts of the dorsal surface. Under side dull 

 brown, base of hairs very little, or not at all, lighter ; extreme 

 tips of hairs generally whitish or greyish white. Tips of wings 

 as in dark-coloured individuals. 



This is very nearly the extreme of the light colour. The hair- 

 bases on the shoulder region and neck are in some specimens still 

 lighter than "wood-brown," almost yellowish white. 



The dark extreme described above and the light extreme here 

 under consideration are very difierent indeed, but there is 

 absolutely no sharp line of separation between them ; they are 

 connected by many intermediate stages. Futting aside all 



Proc. Zool. Soc— 1908, No. XVII. 17 



