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MAALMALS OF AMERICA 



COMMON BROWN BAT 

 Eptesicus fuscus (Bcatiz-ois) 



Other Name. — Big Brown Bat. 



General Description. — A small flying mammal with 

 leather}' membrane stretched across the greatly 

 elongated fingers and extending along sides of body to 

 include the hind legs and tail. Head small ; nostrils 

 simple : eyes minute ; ears large and broad, with a broad 

 tragus or process on anterior part of ear conch; fore 

 limbs elongate with fingers enormously elongated, 

 slender, and only the thumb, which is short and rudi- 

 mentary, provided with a claw : body small and mus- 

 cular, especially thick through the chest: hind limbs 

 much shorter than fore limbs, slender, with five toes, 

 each bearing a claw, the toes of nearly equal length : 

 tail fairly long, nearly half of total length and com- 

 pletely enclosed in the interfemoral membrane; flying 

 membrane extending from the fingers to sides, to the 

 ankle, and thence to include the tail, naked everywhere 

 except for a few scattered hairs on back of interfemoral 

 membrane; body covered everywhere with long soft 

 fur of a brown color, paler below. Strictly a nocturnal 

 mammal and insectivorous. 



Dental Formula. — Incisors, 4^ ; Canines, ^ ; Pre- 



molar';, 



• Incisors, ; Canmes, — ; 



Molars, ^^ = 32. 



Pelage. — Adults: Sexes identical; seasonal varia- 

 tion slight. Everywhere above, dark brown or sepia ; 

 underparts paler; ears and membranes blackish. 

 Yovxc ; Rather darker than adults. 



Measurements. — Total length. 4.5 inches ; tail verte- 

 brae, 1.7 inches: hind foot. .4 inch; forearm, 1.7 inches; 

 spread of wing. 12 or 13 inches. 



Range. — Greater part of the United States and 

 adjoining British provinces. 



Food. — Strictly insect-eating ; mainly small forms 

 caught on the wing. 



Remarks. — There are only five subspecies of the Big 

 Brown Bat found north of the Rio Grande. However, 

 the Bats in general are a very large group containing 

 many forms, some of them bearing considerable super- 

 ficial resemblance to the Big Brown Bat and for this 

 reason are listed in the related species. Most of the 

 Bats found in the United States belong to the same 

 family as the Big Brown Bat. and consequently the 

 relationships are quite close between any two species. 



Rel.vted Species 

 Common Brown Bat. — Eptesicus {=l'espcrtilio) 

 fuscus fuscus (Beauvois). Typical animal as described 



Photograph by J. H. Field 



A NOON-DAY NAP 

 Living Bat of C'^'mmon Brown species, asleep on the top of a post 



