AMERICAN BATS OF THE GENERA MYOTIS AND PIZONYX 125 



conspicuous fringe distinguishes Myotis thysanodes from all other 

 known American members of the genus. In the reduced condition 

 of the secondary cusps and ridges of m} and m?' Myotis thysa/nodes 

 shows the culmination of a series of changes whose earlier stages 

 are seen in M. keemi and whose development may be traced in M. 

 evotis. 



The possibility that Myotis thysanodes is the American representa- 

 tive of the palearctic M. nattereri has been suggested by Thomas.^' 

 The range of the Old "World species is, however, across temperate 

 Eurasia from western Europe to Japan (subspecies toiribvrms) 

 whereas that of Myotis thysanodes in America is more southern, 

 almost subtropical. An equally near relationship is perhaps to be 

 found between Myotis nattereri and M. evotis. The northern limits 

 of these two species in the Old and New Worlds respectively reach 

 about the same latitude, so that the ancestor of M. evotis may have 

 easily invaded North America from Asia during a Pliocene connec- 

 tion of the two continents. Whatever may have been their exact 

 history it seems evident that the three animals represent a common 

 parent stock. 



Two subspecies are recognized: The typical form ranging from 

 Washington and California to northern and central Mexico, and a 

 darker-colored race occurring in southern Mexico and here described 

 as new. 



Habits. — ^Beyond the account supplied by Dr. T. S. Palmer (Miller, 

 1897) of the colony at Old Fort Tejon, Calif., nothing seems to 

 be recorded as to the habits of this bat. Doctor Palmer found this 

 species and M. ywnanensis in numbers in the dark attic of an old 

 adobe house, July 3. Young in various immature stages as well as 

 adults of both species were secured, among which Myotis thysanodes 

 appears to have been in the majority. Dr. Joseph Grinnell visited the 

 locality 13 years later but failed to find this bat. On September 28, 

 1903, James H. Gaut, collecting for the United States Biological 

 Survey, obtained several in the ruins of Gran Quivera, Mesa Jumanes, 

 N. Mex. A note on the label of specimens collected by Salle in 

 Oaxaca in 1857, states that they too were found in an old ruin. The 

 late Dr. E. A. Mearns captured two adult females on June 28 in 

 the San Luis Mountains (on the Mexican boundary) that contained 

 each a large fetus nearly ready for birth. During the breeding 

 season the females appear to remain in colonies by themselves apart 

 from the males until late summer at least. Such a breeding colony 

 was discovered by Mr. Vernon Bailey on August 9, 1913, at Clover- 

 dale Hills, N. Mex., and 83 specimens were preserved, most of them 

 in alcohol. An examination of these, evidently taken at random, 



»»Proc. Zool. Soc. London, 1905, p. 388. 



