A MONOGRAPH OF THE l^ATS OF NORTH AMERICA. 13 



last named on the upper surface of the interfenioral membrane. The 

 very long hairs of the sides of the muzzle, whii-h are so conspicuous in 

 many of the small mammals of other orders, notably the liodentia and 

 Carnivora are absent. The best exami)les are met with in Vcspertilio 

 and Ghocronycteris. Fring-es of bristles adorn the margins K)f the toes 

 in ]Molossi. 



In describing bats in this manner the attention which has been given 

 to the details of the coloring and the markings on membranes require 

 an exact use of terms. 



When hair arises from the membrane it will be seen that the clumps 

 follow the directions of the trabecuhe and are detected in the trans- 

 lucent wing as minute black dots arranged in rows. These must not 

 be confounded with i^igment spots which dot the naked spaces of the 

 wing in some species. 



GLANDS. 



The skin glands are best developed on the sides of the face directly 

 back of the muzzle. In Molossi a large, median, coarse sebaceous gland 

 lies depressed on the under surface of the neck. It is best developed 

 in the male. An elevated thoracic medianly placed gland is present in 

 Amefrida. The mamma», are large during the lactating period ^\'hen the 

 nii)ples are projecting and the aveolar space naked. At other times 

 the nipple disappears and the gland is reduced to the smallest possible 

 proportions. In Saccopferyx and its allies the wing membrane above 

 the anterior extremity is furnished with a sack which is lined with folds 

 which yield a fetid secretion. The position and size of this sack furnish 

 excellent characters to distinguish genera as well as sexes of individ- 

 uals. 



COLORATION. 



It is necessary to state that the colors for the most part are described 

 from alcoholic specimens which have been removed from the spirit and 

 permitted to dry. Mr. F. W. True writes in the Smithsonian Eeport 

 for 1888 that alcohol disturbs the color-scheme of a mammal. The 

 character of alcohol is not especially here named and tlie remark is 

 undoubtedly correct for specimens which have been preserved in wood 

 spirit. However, none of the specimens used for this study have been 

 l^reserved in other than commercial alcohol which has been variously 

 diluted with water. I have observed no differences of the kind named 

 between the few living individuals I have seen, the fur of the dried 

 skin prepared in the usual way with arsenic and in skins dried after 

 prolonged immersion in commercial spirit. It must also be remembered 

 that since all the material available has been preserved in the same 

 medium the comparisons are suffuiieutlj^ exact for purposes of identifi- 

 cation of museum alcoholics. It is barely possible that the color de- 

 scription may require modification as contrasted with that based upon 

 living specimens. 



