AMERICAN BATS — HANDLEY 139 



Mexico and specimens of P. townsendii (AMNH 142023, USNM 

 297710) from West Virginia; in these the temporal ridges are contigu- 

 ous but not coalesced). 



The presence of supraorbital ridges is interpreted as a primitive 

 characteristic. They are present in Euderma maculatum, Plecotus 

 auritus, and P. phyllotis. They are absent in P. mexicanus, P. 

 rafinesquii, and P. townsendii. Separate temporal ridges, also con- 

 sidered to be a primitive characteristic, are observed in Euderma macu- 

 latum and in Plecotus 2)hyllotis', they unite to a common crest in the 

 other Recent species of the genus Plecotus. 



Other cranial characters relate P. alleganiensis closely to the Recent 

 species P. rafinesquii and P. townsendii. The rostrum is relatively 

 broad and flattened; the anterior nares are enlarged; the rostral 

 profile is almost straight (normally, though not invariably, concave 

 in P. townsendii virginianus, and normally almost straight in P. 

 rafinesquii). The palate and basicranimn are smiilar to those of 

 Recent species of the subgenus Corynorhinus ;hsisia\ pits are prominent. 



General proportions of the skull of P. alleganiensis are the same as 

 in P. t. virginianus; the brain case may be a trifle shallower. Depth 

 of the brain case is difiicidt to assess in the only specimen in which 

 it is intact, however, for the posterior part of the skull has been 

 compressed (the occipital condyles are in the plane of the basioccipital- 

 basisphenoid plate, the foramen magnum is in almost the same plane, 

 and the supraoccipital, rather than being almost vertical to the main 

 axis of the skull, has its lower margin tilted forward about 30°). 



The upper dentitions of Recent P. t. virginianus and fossil P. 

 alleganiensis are indistinguishable. None of the 27 mandibidar frag- 

 ments of P. alleganiensis is complete, but all parts of the lower jaw 

 are represented. Differences between the mandibles of P. alleganien- 

 sis, P. townsendii, and P. rafinesquii are slight. The masseteric 

 (coronoid) fossa is usuaUy deeper and better defined in the fossil, 

 and the mandibular foramen lies more posteriorly and lower, nearer 

 the base of the angular process; the canine averages larger in diameter 

 at the cingulum; Pi averages slightly larger; and the molars average 

 slightly broader — in essence, the dentition of P. alleganiensis is slightly 

 more robust. 



P. alleganiensis differs markedly from the other Pleistocene species, 

 P. tetralophodon, in having the skull apparently broader, the supra- 

 orbital region ridged, the temporal ridges farther apart, and the fourth 

 commissure of M^ barely indicated. 



Relationships: P. alleganiensis shares many morphological fea- 

 tures with the two Recent species of the genus that now inhabit the 

 eastern United States. It could have been directly ancestral to either 

 or both of these species. Relationship of P. alleganiensis to the 



