88 BULLETIN 43, UNITED STATES NATIONAL MUSEUM. 



ing Spix's form to the same species as Geoffroy's. I liave examined 

 specimens of V. albescens in the JSI^atioual Museum which have been re- 

 ceived from the British Museum, and assuinablyare the same as those 

 iu\med by Dobson, that I am of the opinion that since in America no b.at 

 is known in which the fur of the under surface is black, that V. hrasUi- 

 ensis is the same as V. albescens. 



It is important to ascertain the places of variation in this obscure 

 species and a few notes on individuals are herewith appended. In No. 

 20840, Iveeler County, Calif., collectiou of A<>ri(niltural Department, the 

 foot presented the extreme measurement of 10""" while the forearm was 

 35"'"', the length of the head and body 45"'"', and the tail 30'""'. Yet with 

 these dimensions the thumb was 5"'"' long only, and the ])ostcalcaral 

 lobe was absent. Of the phalanges of the manus those of the secoud 

 row were scarcely shorter than those of the iirst, the greatest dispropor- 

 tion being noticed in the lifth digit when the lengths were as 8"'"' to 5"'"'. 

 In No. 29855, Old Fort Tejon, Calif., ibid.., the individual was smaller. 

 The forearm was 32"'"' long, the foot 8.^"'"'. The head and body was 39""" 

 long, the tail 36™'", the thumb remaining the same, viz, 5"'"'. There was 

 no postcalcaral lobe. The differences in the relative lengths of the 

 digits were greater than in No. 29840, in the third digit being 10'""' to 

 8^""", in the fourth 8""" to 6'"'", and in the lifth 8""" to 4"'"'. In No. 

 27974, .$ Colorado River, Nevada, ibid., the forearm was 31i"'"' long, 

 the foot 8'"'", the thumb 5'"'", the head and body 38""", the tail 29"""; 

 while the phalanges of the third and fourth were equal, in the fifth the 

 proportions were as Gi'""' to 4i™™. 



If these proportions were constant, specific distinctions could easily 

 be drawn. But unfortunately they are not so, and no two individuals 

 will be found to conform to any diagnosis for specific characters Avhich 

 I have endeavored to frame. The auricle varied in detail on the outer 

 border, especially as to the Avidth of the first scallop and the tip. Pe- 

 culiarities probably obtain according to altitude, character of food, 

 degree of humidity in the atmosphere, etc. In No. 28972, Lone Pine, 

 Calif., collection of Agricultural Department, the proportion of the tail 

 to the body was as 32""" to 39'""', a great contrast to the foregoing phase. 

 In No. 315G9, San Emigdio, Calif., iMd., the membranes and ears were 

 black. The forearm Avas 30^""", being the greatest length of any indi- 

 vidual examined in the United States (one specimen from Mexico meas- 

 ured 41'""'). The thumb was remarkably small, being 4i'""', while the foot 

 was 8i'""^. The length of the body was 49"'™ and that of the tail 43""", 

 thus being ami)le. The phalanges were subequal <'xcepting those of the 

 fifth digit, where the values were as 9"™ to 6""". This variety is too large 

 for the type of Y. melanorhinus. It it like V. albescens in having bluish 

 translucent wings as in the diagnosis, but differing in the presence of 

 large yet delicate frame and in greater deposition of pigment. Some 

 of the black phases are noted as being fi)und in growths of juniper. 

 Is it possible tluit it is a mountain variety and that V. evotis is a phase 



