72 BULLETIN 43, UNITED STATES NATIONAL MUSEUM. 



glands distinct, nodular. Postmen tal wart constitute s a large, hard nodnle. Thumb 

 directed outward, scarcely larger than its metacarpal bone; callosity large. 



V. nattereri (Europe). — Nostril as in F. muricola; muzzle and post ment.il glands 

 rudimental. Internal margin of the auricle and internal basal lobe not lying against 

 the head. Outer margin of the base of the tragus obscurely separated from the 

 inconspicuous lobule. Tragus greatly produced, filiform. First metacarpal bone 

 strongly tlexed, outline defined ; callosity small. Thumb scarcely if at all projected 

 beyctnd the contour of the second metacarpal bone. Oblique tibial line arises from 

 the distal third of the tibia. 



J', capaccinii (Europe). — Feet enormous; tragns long, filiform; membrane from 

 ankle, or a point slightly above it, covered with hair which also clothes the leg and 

 the sides of the interfemoral membrane. 



r. viystacinus (Europe). — As opposed to the preceding this species is not so 

 easily distinguished from the American species (vide ]Monograi)h). The tragus is 

 quite as in the phases of our Western States. The fur presents some distinctive 

 features, viz, in the different hues of brown of the back. 



The American species further resembles Y.myfitacmus in the bearded 

 tipper lip, especially the western forms, as stated in Monograph, ^. GO. 

 In alcoholic specimens this is less conspicnons than in the dry, for the 

 hairs are soft and readily cling- to the skin. In some varieties the hairs 

 qnite thickly clothe the sides and front of the face, and are conspicuous 

 from their black color. Apart from the wing membrane this is the best 

 jjeripheral character by which VespertiUo can be distinguished from 

 Adclonycteris and Vespenigo. 



The difficulties acknowledged in identifying the American species 

 are apparently insuperable, so great is the range of variation in the 

 proportions of the ears, thumb, feet, tail, and phalanges of the manus, 

 and in the coloration of the fur and the membranes. If the purposes 

 of zoological science should end with the identification of species, the 

 student might well be discouraged in his studies in this field. But 

 fortunately the very intricacies of the subject suggest problems, in the 

 attempts to solve which, his knowledge of the life and structure of these 

 little organisms can not fail to be Increased. 



After careful consideration from the available material, I have con- 

 cluded that there are three species of YespertUio in the United States, 

 namely, V. (jrypliuH^ inhabiting the country east of the ninety-eighth 

 degree parallel longitude; T^ albescens, and V. nitidus, in the country 

 west of the line above named. 



Numerous variations exist which make it unsatisfactory to frame 

 diagnoses of these species after the manner seen elsewhere in this 

 memoir. Such variations are of great interest, and it will be found con- 

 venient to retain for them names of well-marked varieties as though 

 they had specific value. Among such I include V. lucijugus under F. 

 (jryphus; V. melanorhinus under 1". albescens; V. macropus under V. albes- 

 cens; V. evotis under V. albescens; V. longicrus under V. nitidus; Y. yu- 

 manensis under V. nitidus. 



Variations in animals are commonly included under the headings of 

 the regions of country in which they occur and by which their distri- 

 bution is limited. While varieties so defined are doubtless the main 



