136 PROCEEDINGS OF THE NATIONAL MUSEUM vor-. iio 



Subgenus Corynorhinus H. Allen 



Vesperiilio Rafinesque, 1818, p. 446. (Part.) 



Plecotus Lesson, 1827, p. 96. (Part.) 



Synotus Wagner, 1855, p. 720. (Part.) 



Corynorhinus H. Allen, 1865, p. 173. 



Corynorhynchus Peters, 1865, p. 524. (Nomen nudum.) 



Corinorhinus Dobson, 1875, p. 348. 



Type species: Plecotus macrotis LeConte. 



Distribution: Temperate North America in Lower Austral and 

 Lower Sonoran to Canadian life zones from Virginia, Ohio, Illinois, 

 Kansas, South Dakota, Idaho, and British Columbia south to the 

 Gulf of Cahfornia and the Gulf of Mexico and through the Mexican 

 Highlands to the Isthmus of Tehuantepec (fig. 27). 



Description: Supraorbital region smoothly rounded or faintly 

 ridged (fig. 4); temporal ridges remain apart or coalesce to form a 

 sagittal crest; rostrum broad compared ^vith other subgenera of 

 Plecotus, flattened, and with slight middorsal concavity; brain case 

 relatively narrow and deep; zygoma relatively thin and fragile in 

 appearance, with postorbital expansion in posterior third of arch; 

 median postpalatal process a prominent spine; basial pits prominent; 

 auditory buUa circular in outline. 



I* with or without accessory cusp (fig. 2); P^ small, barely exceeding 

 cingulum of canine in height; P* wider than long; space between 

 posterointernal edge of P* and anterior edge of M' only about one- 

 third lingual length of P*; third commissure of M^ equal to or longer 

 than second commissure; metacone of M^ fairly prominent; Pi only 

 slightly larger than P3; P4 single-rooted, much shorter in antero- 

 posterior diameter at the cingulum than the tooth is high. 



Glandular masses resembhng thumbless mittens, rise from sides of 

 muzzle (fig. 7); nostril without cornu and with posterior elongation 

 (fig. 8); auricle with anterior basal lobe reduced to a small lap of 

 membrane near tragus (fig. 9); accessory anterior basal lobe absent; 

 transverse ribs on auricle interrupted by vertical rib near posterior 

 border of auricle; tragus relatively narrow and long; second phalanx 

 of third digit longer than first phalanx (fig. 6); forearm averages 

 relatively long; calcar not keeled; interfemoral membrane attached 

 to tip of last caudal vertebra. 



Key to species of the subgenus Corynorhinus 



1. M* with 4th commissure almost as long as 3rd (Pleistocene species). 



P. tetralophodon (p. 140) 

 M* with 4th commissure barely indicated or absent 2 



2. Supraorbital region faintly ridged, those ridges continuous with the temporal 



ridges, which do not coalesce to form a sagittal crest (Pleistocene species) . 



P. alleganiensis (p. 137) 



