74 BULLETIN 43, UNITED STATES NATIONAL MUSEUM. 



brane, tlie proportion of the wings and the details of the skeleton and 

 of the teeth are precisely those of ]". gryphus. 



The pedouiorphic varieties of V. fjryphiis appear to be more common 

 in cold, elevated countries than in warmer. The retardation may be 

 due to the environment being- unfavorable to developmeiit, owing to a 

 short summer and a correspondingly long i)eriod of hibernation. This, 

 however, is a, surmise, as excellent examples are met with in V. al- 

 bescens along the southern parts of California and in Lower California. 

 The markings of the membranes in pedomorphism are precisely those 

 of the typical adults. The characters which may be retarded are, of 

 course, infinite. In point of fact, however, those which are usually 

 foun<l associated are those above named. Occasionally a small ear and 

 tragus is found with a small foot and large inter femoral membrane. 

 The opposite to this I have not seen, namely, a large foot with a large 

 ear, tragus, and iuterfemoral membrane. 



Melanic variation. — When the pigmentation is everywhere so great 

 as to give a black hue to the membranes, ears, face, and feet, the con- 

 trast is so great between the individuals and those which exhibit the 

 translucent black sha'des as to be very noticeable. Since the intensely 

 black forms include those which also x)ossess auricles which are mod- 

 erately or scarcely concave on the outer border, and which are larger 

 than the head, they constitute true varieties. V. evotis and V. mela- 

 norhinus are melanic varieties of V. albescens. V. longicrus True is 

 probably a melanic variety of V. nitidus. Melanic variation is less 

 common in V. gryphus than in either of the western species. In no in- 

 stance does it enter into a diagnosis. Black varieties through the 

 fauna may be found in both the typical and the pedomorphic adults. 



It is difl&cult to determine the examples of Vespcrfilio from the coun- 

 try west of the ninety-eighth parallel. The change of coh)r of fur and 

 membrane, the variation in the shapes of the iuterfemoral membrane, 

 the relative lengths of the limbs, especially of the thumb, feet, and 

 legs, are unavailable for purposes of diagnosis. 



I assume that the following characters determine the western spe- 

 cies: Lateral upper incisor much less frequently crenulated at cingulum 

 than in the eastern forms, and disposed to inward rotation. Penis 

 small, with narrow, often pigmented prepuce. Fur forming a transverse 

 white line under the Iqwer jaw. Tragus not isosoles, but straight on 

 inner border and convex at lower part of the outer border. If the outer 

 border is without concavity above this convex portion, then the tragus 

 is semielliptical; if the border is with concavity, then the tragus is 

 semipyriform. The membranes are translucent, never brown in tint, 

 but when not melanic are of a peculiar blueish-black, gray tinge. Re- 

 finesque describes a species of ISTorth American Vespertilio under the 

 name of V. cyanopterus, which I have been unable to identify. (See 

 Appendix.) The " wings are of a dark blueish gray." The ditterence be 

 tween a dark bluish gray and a diluted translucent black is, perhaps, 



