NEW BATS FROM PANAMA — HANDLEY 469 



missure shorter than first; hypocone much reduced on M 1 and M 2 ; 

 P 4 double rooted. Rostrum broad and deep; lachrymal ridge not 

 developed; braincase narrow, deep, and tilted up away from plane of 

 palate. Otherwise similar to Lasiurus borealis. 



Measurements of holotype: Total length 112, tail vertebrae 

 48, hind foot 11, ear from notch 14, forearm 44.8, tibia 19.5, calcar 

 15.1. Greatest length of skull 13.0, zygomatic breadth 9.9, inter- 

 orbital breadth 4.2, braincase breadth 7.6, braincase depth 6.2, 

 maxillary tooth row length 4.7, postpalatal length 5.7, palatal breadth 

 at M 3 6.7, rostral breadth at canine 5.7. 



Comparisons: Lasiurus castaneus is a member of the borealis group. 

 Its coloration is unique, and extreme tilting of the braincase rlative- 

 to the palatal plane and reduction of parts of the upper molaers like 

 wise set it apart from other species of the borealis group. In overall 

 size and in size of auricle and antitragus it resembles the remote 

 northern borealis and southern varius, but its wings are unusually 

 long. Like seminolus it lacks development of a lachrymal ridge, 

 has a black face, and has the median band of the dorsal hairs reduced. 

 Like varius it has black ears and membranes and darkened face. It 

 scarcely needs comparison with the sympatric Jrantzii, which is much 

 smaller, paler and brighter colored, and plain faced and has a glo- 

 bose braincase and a shorter, narrower rostrum. 



Remarks : Variation in coloration is remarkably slight in the borealis 

 group. Specimens from California (teliotis), Central America (Jrant- 

 zii), and Chile (varius) are scarcely distinguishable colorwise. Dif- 

 ferentiation in coloration has occurred in the extreme northeast 

 (borealis) and extreme southeast (blossevillii) along similar lines — 

 overlay of the red mass effect with white (sort of a "frosting"). 

 < 'astaneus in Central America, seminolus in the northeast, and perhaps 

 egregius in Brazil, appear to be independent variables. Sexual 

 dimorphism in size and coloration is marked in borealis and seminolus 

 but is slight in western North America, Central America, and South 

 America (see also table 2 on next page). Extension of fur onto the 

 membranes varies with latitude and perhaps with altitude (more at 

 higher latitudes, less at lower latitudes) and is of limited taxonomic 

 value. 



Bats of the mainland of North and South America that belong to 

 the Lasiurus borealis group are: 



Lasiurus borealis blossevillii Lesson and Garnot : Type locality, 

 Montevideo, Uruguay (bonariensis Lesson, Buenos Aires, Argentina; 

 enslenii Lima, Sao Lourengo, Rio Grande do Sul, Brazil; and salinae 

 Thomas, Cruz del Eje, Cordoba, Argentina, are probably synonyms). 

 diagnosis: slightly larger than Jrantzii, smaller than varius (larger 

 toward the south) ; dorsum washed with whitish ("frosted") ; reddish 



