204 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



incipient postorbital process; upper surface of rostrum with distinct 

 concavity on each side between lachrymal region and nares; other 

 features of skull essentially as in Myotis, except for a general tendency 

 toward broadening and shortening. Ear short, nearly as broad as 

 long, the tragus short, straight, and bluntly rounded, its width more 

 than half length of anterior margin. Interfemoral membrane furred 

 on basal half above. 



Species examined. — Lasionycteris noctivagans (Le Conte). 



Remarks. — In its dention, Lasionycteris very closely resembles 

 Myotis, differing only in the absence of the small, middle upper 

 premolar. In the form of the skull 'and in the peculiar short, broad 

 ears it shows greater specialization than some of the genera with more 

 highly modified teeth. 



Genus PIPISTRELLUS Kaup. 



1829. Pipistrellus Kaup, Skizzirte Entwick.-Gesch. u. natiirl. Syst d. europ. 

 Thierw., I, p. 98 (pipixtrcllus). 



1837. Pipistrellus Bonaparte, Icon, clella Fauna Ital.. I, fasc, XX. 



1838. Romicia Gkay, Mag. Zool. and Bot, II, p. 495, February, 1838 (calca- 

 rata=inhlH) . 



1839. Vcrperuuo Keyserling and Blasius, Wieginann's Arehiv fur Natur- 

 geschichte, 5ter Jahrg., I, p. 312 (part). 



1840. Ifowiriim Blyth. Cinder's Animal Kingdom, p. 75. 



1856. Hypsugo Kolenati, Allgem. deutsch. naturhist, Zeitung, Dresden, neue 



Folge, II, p. 131 (maurus and krascheninikov i i ) . 

 185(1. Nannugo Kolenati, Allgem. deutscb. naturhist, Zeitung, Dresden, neue 



Folge, II, p. 131 (nathusli, pipistrellus, and kulilii). 

 1864. Scotophilia II. Allen, Monogr. Bats N. Amer., p. 27, June, 1864 



(part). 

 1871. Pipistrellus Dobson, Proc. Asiat. Soe. Bengal, p. 213. 

 1878. Vesperugo Dobson, Catal. Chiropt. Brit. Mus.. p. 183 (part). 

 1894. Vesperugo H. Allen, Monogr. Bats N. Amer. (1893), p. 121, March 



14, 1894. 

 1897. Pipistrellux Miller, Ann. and Mag. Nat. Hist., 6th ser.. XX. p. 384, 



October, 1897. 

 1897. Pipistrellus Miller, North Amer. Fauna, No. 13, p. 87, October 16, 



1897. 



Type-species. — Vespertilio pipistrellus Schreber. 



Geographic distribution. — Entire mainland of Eastern Hemisphere 

 to limits of tree growth, also Malay Archipelago, New Guinea, Solo- 

 mon Islands, and northern Australia; in America from northern 

 United States (except in boreal zone) to southern Mexico. 



Number of forms. — About 40 species of Pipistrellus are now recog- 

 nized. 



Characters. —Dental formula: 



- 2 :). 1. - 2 - -4_5 67 . 2_- 2 1 - 1 2-2 3-3 



1 2 3. 1. - 2 - 4 56 7 ' 3 - 3' '' 1 -V^ m 2 '- 2' '" 3 - 3 = U - 



