128 



PROCEEDINGS OF THE NATIONAL MUSEUM 

 7CP 



Figure 11. — Distribution of Plecotus, showing coincidence with the North Temperate Zone 

 (here defined as a region having an average annual temperature between 35° and 

 70° F.). 



Upper incisors not in line with remainder of tooth row (lingual); 

 I^ simple or bifid (fig. 2), much larger than P; P not touching canine; 

 P^ small; hypocone absent and protocone reduced posteriorly in M^ 

 and M^; size of third commissure and metacone variable in M^; lower 

 canine much exceeding P4 in height, and possessing a well defined, al- 

 though small, anterointernal basal cusp; Pi and P3 small and crowded 

 or not; P4 single-rooted or double-rooted and lacking a weU defined 

 metaconid cusp. 



Muzzle provided with dorsolateral glandular masses which in some 

 forms rise above the muzzle as peculiar lumps (fig. 7) ; nostril openings 

 small and of primitive vespertilionid type or large, opening upward, 

 and peculiarly extended posteriorly (fig. 8); auricle and tragus large 

 (fig. 9) ; tragus provided with a prominent basal lobe, and not united 

 with posterior basal lobe of auricle; anterior basal lobe of auricle 

 normal, expanded, or reduced; transverse ribs on auricle variable in 

 posterior extension; second phalanx of third digit longer or shorter 

 than third phalanx (fig. 6); calcar keeled or not; interfemoral mem- 

 brane attached to base or tip of last caudal vertebra; coloration brown, 

 without pattern, except for ventral paUor; membranes and ears 

 brownish. 



Key to subgenera of Plecotus 



1. Nostril unspecialized; accessory basal lobe of auricle developed into a projecting 

 lappet; calcar keeled; brain case broad (53 percent of greatest length). 



Subgenus Idionycteris (p. 129) 



Nostril with posterior elongation and reduction of cornu; accessory basal lobe 



of auricle absent or only slightly developed; calcar not keeled; brain case 



narrow (averaging 48-50 percent of greatest length) 2 



