AMERICAN BATS — HANDLE Y 141 



Relationships: Plecotus mexicanus and P. iovmsendii now inhabit 

 the region where the fossU P. tetralophodon was found. P. tetralopho- 

 don must have been closely related to these species, for the general 

 conformity of the skull is similar in all three; probably all came from 

 a common stock. I do not believe that P. tetralophodon is directly 

 ancestral to either of these Recent species, however. It is less like 

 P. rafinesguii and P. alleganiensis. 



Specimen examined: The holotype. 



RECENT SPECIES 



Plecotus mexicanus CM. Allen 



Corynorhinus macrotis pallescens Miller, 1897, p. 52. (Part.) 

 Corynorhinus megalotis mexicanus G. M. Allen, 1916, p. 347. 

 Corynorhinus rafinesguii mexicanus Miller, 1924, p. 83. (Part.) 

 Plecotus rafinesquii mexicanus Dalquest, 1953, p. 64. (Part.) 

 Corynorhinus mexicanus Handley, 1955c, p. 148. 



Holotype: USNM (Biol. Surv. Coll.) 98285; adult female, skin 

 and skull; collected 25 August 1899, by E. W. Nelson and E. A. Gold- 

 man; near Pacheco [Sierra de Brena, 8,000 feet]. Chihuahua, Mexico; 

 collector's No. 13955. 



Distribution: The higher and more humid parts of the Sierra 

 Madre Occidental, the transverse volcanic belt of central Mexico, 

 and the Sierra Madre Oriental (jSg. 15). North to El Tigre Moun- 

 tains, Sonora; near Pacheco, Chihuahua; and 22 miles south-southeast 

 of Monterrey, Nuevo Le6n. South to Pdtzcuaro, Michoacdn; Monte 

 Rio Frio, 28 miles east-southeast of Ciudad Mexico; and Jico, Vera- 

 cruz. Zonal Distribution: Mostly Transition and Upper Austral. 

 Altitudinal range from 4,800 feet to 10,500 feet; usually above 6,000 

 feet. 



Description: Adult coloration: Tips of hairs of upperparts vary 

 from Verona Brown to Fuscous, bases from Bone Brown to Fuscous- 

 Black; degree of differentiation between tips and bases of hairs slight; 

 burnishing of hair tips absent or only slightly evident in most speci- 

 mens; hairs at posterior base of auricle paler than remainder of dor- 

 sum. Bases of hairs of underparts vary from Benzo Brown to Fuscous, 

 tips are about Pale Pinkish Cinnamon. Immature coloration: Dor- 

 sum smoky brown, similar to coloration of some adults. 



Size small for subgenus; lobes of presternum slightly expanded; 

 forearm averages relatively long; brain case averages relatively wide 

 and deep, sloping up abruptly above the short, depressed rostrum; 

 anterior nares, viewed from above, usually relatively small and angu- 

 lar in posterior outline; median postpalatal process varies from styli- 

 form to triangular; auditory buUa averages relatively small. First 

 upperf incisor usually with^af prominent accessory cusp and always 



