118 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



Eptesicus are not suitable for such a comparison because of the prob- 

 ability that they are polyphyletic aggregations, and not natural 

 groups. Most of the other vespertilionine genera are either monotypic, 

 consist of slightly differentiated species, are of disputed validity, or 

 are not sufficiently well known. The American genus Lasiurus is a 

 notable exception, being well known, widely distributed, and contain- 

 ing several well-differentiated species. Included in the genus are the 

 red bats (Z. borealis, etc.), hoary bats (L. cinereus, etc.), and yellow 

 bats (L. ega, etc.). The magnitude of the differences distinguishing 

 these species equals or exceeds the magnitude of the differences dis- 

 tinguishing the species Plecotus phyllotis, P. auritus, and P. townsendii 

 (compare tables 2, 3, and 4). 



Status of Genus Barbastella: Miller (1907, p. 224) pointed out 

 the likeness of Barbastella to Euderma and Plecotus, whereas Tate 

 (1942, p. 230) tried to show that any relationship between Barbastella 

 and these genera is remote. Tate believed that Euderma and Plecotus 

 are derivatives of the Myotis stem, and he supposed that Barbastella 

 came from the Pipistrellus stem. 



The strongest resemblances of Barbastella to Pipistrellus are in 

 tooth formula, and in the posterior shortening of the palate, which 

 extends only a short distance past M^. Like Pipistrellus, but also 

 like Myotis as well, Barbastella has small, relatively simple auditory 

 bullae; fragile, much-reduced zygomata without postorbital expan- 

 sions; and a short angular process of the mandible. The few resem- 

 blances of Barbastella to Pipistrellus and its relatives seem to lose 

 much of theu' significance, however, in view of the many similarities 

 of Barbastella to Euderma and Plecotus: 



1. Rostrum relatively narrow and weak. 



2. Brain case elongated and vaulted in frontal region. 



3. Zygomata (in dorsal aspect) parallel and not bowed out posteriorly. 



4. Coronoid process of mandible high. 



5. Dentition weak. 



6. Cusps of teeth high and sharp. 



7. Lower incisors graduated in size (1$ large to Ii small) . 



8. I3 with prominent extra internal cusp (total of 4 cusps). 



9. Lower canine with prominent anterointernal basal cusp. 

 10. P4 not so high as Mj. 



The resemblance of the teeth in Barbastella, Euderma, and Plecotus 

 is particularly striking. In shape and proportions, the teeth of these 

 genera are almost identical. The facts that one of the upper pre- 

 molars (P^) has been crowded out of the tooth row and that one of 

 the lower premolars (P3) has been eliminated in Barbastella are not 

 sufficient in themselves to indicate that Barbastella is closely related 

 to Pipistrellus. (Note that Euderma also has the same dental for- 

 mula as Pipistrellus.) 



