326 PROCEEDINGS OF THE ACADEMY OF [1889. 



free border. The postdigital arises high in the interspace apparently 

 from the palm, approaches the fourth metacarpal bone at its prox- 

 imal end but soon leaves it and is distributed to the anterior half of 

 the interspace. 



The third interspace shows a delicate line from the first inter- 

 phalangeal joint of the fourth finger and a second longer one from 

 the metacarpophalangeal joint of the third finger. 



The interfe moral membrane shows the oblique line above called 

 subtibial but in this form it is caudotibial since it arises from 

 the side of the first caudal vertebrse. 



The terminal phalanges much the same as in Atalapha. The 

 parts are all delicate ; the terminal phalanx of the third digit is 

 sigmoid and less rigid than in any species examined. The tip of the 

 terminal phalanx of the fourth digit is minutely lobed and free. 



The markings in Vesperus, Vesperugo, and Vespertilio are 

 among the most intricate of any in the order. My material has 

 not enabled me to do more than give a general idea of the parts. 

 The characters appear to be more sharply defined in Vespertilio 

 than in Vesperus, and often yield good characters in separating species, 

 As may be expected the American species are the most difficult. I 

 may here mention that owing to the close resemblance in general 

 appearance and similarity of habit of Vesperugo georgianus and 

 Vespertilio subulatus the two species are frequently found in the 

 same jar and both receive the name of the commoner form, V. sub- 

 ulatus. Brief examination is alone required to separate them. The 

 two predigitals and absence of the postdigitals in the fourth interspace 

 of Vesperugo georgianus being easily separated from the symmetrical 

 arrangement in Vespertilio subulatus. 



Vesperus fuscus. 



The parts throughout much the same as in L. noctivagans. There 

 is a small oblique band at the muscle-mass at proximal end of the 

 fifth metacarpal bone on the mesopatagium and one on the fourth 

 interspace. The intercostal lines five in number. The postdigital 

 as a rule appears as one of two terminal branches which arise from 

 a common trunk in the angle formed by the approximation of the 

 fourth and fifth metacarpal bones. The line may in some instances 

 approach the fourth metacarpal and in some the fifth, when the 

 arrangement resembles that of Vesperugo georgianus. The predig- 



