A MONOGRAPH 7 THE BATS OF NORTH AMERICA. 105 



Previous to the date of the Mouograph of 1864, this genus had been 

 embraced in Vespertilio. In cousidering- it a species of 8cot(q)hilus I 

 made an error. The difference in the number of the molars, the two 

 genera, should have iulluenced me in not including the form in any of 

 the genera known at that time. '' The trifling difterence in the number 

 of the teeth does not afford a sufticient reason for considering them (the 

 North American Vespertilionine species) as different" (Leconte). I 

 was influenced by tliis opinion in not separating Lasionycteris from its 

 congeners. While Maj. Leconte, a leading authority in his day, was so 

 doubtful upon the subject of the value of the variations in the dental 

 formula he placed great importance on the minute changes in form of 

 the outer ear. 



1. Lasionycteris noctivagans (Leconte). The Silvery Bat. (I'lates xiii, xiv.) 



VeapertUio noctiva[/ans Lecoute, Cuv. An. Kingdom (McMurtrie's ed.), i, June, 1831, 



31; Cooper, Ann. Lye, Nat. Hist. N. Y., iv, 1837, 59; De Kay, Nat. Hist. N. Y. 



(Zonl.), 1842, 9, PI. I, ¥ig. 1; Wagner, Schreb. Sangeth., Siippl., v, 18c.5, 754. 

 Vespertilio auduhoni Harlan, Month. Amer. Jour. Geol. Nat. Hist., i, 1831, 220, PI. ii; 



lb., Med. and Physical Researches, 1835, 30, PL iv. 

 Vespertilio pulverulcntus Temmiuck, Monog. Mam., ii, 1835, 235; Leconte, Proc. 



Acad. Nat. Sci. Phila., 1855, 436; Max. zu Wied, Archiv Naturg., 1861, 192. 

 Scotophilus noctivagans H. Allen, Monog. N. A. Bats, 1864, 39. 

 Lasionycteris noctivagans Peters, MB. Akad. Berlin, 1865,648; Merriam, Mamm. Ad- 



* iroudack Region, 1886. 

 Vesperides noctivagans Coues and Yarrow, Wheeler's Exped., Zoiil., 1875. 

 Vesperugo noctivagans Dobson, Cat. Chirop. Brit. Mus., 1878, 238. 



Description — Ear oval. Internal basal lobe of dull yellow color which 

 contrasts with the dark brown of the rest of the auricle. The free pro- 

 jecting lobe rather larger than in other species of the group. The 

 lobe ends abruptly on the inner border, which is directed in an 

 oblique straight line upward and backward to a blunt tip which is in the 

 long axis of the auricle and is not directed backward. Tlie upper part 

 of the outer border is straight and bears a d<']icate fold which is turned 

 back against the posterior surface of the auricle. Tlie lower part is 

 convex, also bears a delicate reverted fold, and is separated from the 

 upper by a small notch. The external basal ridge does not reach the 

 border of the auricle. It is irregular and bears two tubercles, between 

 which lies a well-defined pocket. The external basal lobe is membranous 

 and bears upon its inner surface a small nodule which is lionKdogous to 

 th(^ reverted portion in AdeJonyelcris fuscus. The exteinal basal lobe 

 ends on a post rictal wart. 



Thus the ear has a membranous expansion of variable width on the 

 posterior border from the tip to the angle of the mouth. 



Tragus short and blunt, straight on the inner border, slightly deflected 

 outward at the outer border lor a short distance, and is thence abruptly 

 convex, to be gradually inclined inward at the pedicle. The outer sur- 

 face of tragus is concave and snggests in a general way the plan in 

 Emballonura. Glandular masses on side of snout cofJispicuous; they 



