1889.] NATURAL SCIENCES OF PHILADELPHIA. 313 



ON THE TAX0N3MIC VALUES OF THE WING MEMBRANES AND OF 



THE TERMINAL PHALANGES OF THE DIGITS IN 



THE CHEIROPTERA. 



BY HARRISON ALLEN, M. D. 



When a bat with outstretched wing is held between the eye of the 

 observer and a bright light the membranes are seen to be traversed 

 by numbers of lines. Many of these are delicate trabecular of con- 

 nective tissue, — in some instances continuous with the fascia of the 

 forearm, or palm, in others with the capsules of the joints. They 

 can be seen in some examples passing obliquely from the third meta- 

 carpal bone over the palmar surface of the fourth to the membrane 

 between the fourth and fifth bones. The wing membrane is strength- 

 ened at the free margin by several trabecular which pass from the 

 tibia at a point near the ankle to the second digit of the fifth finger. 

 The course of vessels can be traced, as, for example, from the elbow 

 forward and downward on the wing membrane, and on the inter- 

 femoral membrane. Tendons can be seen, as the tendon of the 

 biceps at the elbow, that of the occipito-pollicalis, that of the flexor 

 carpi-radialis at the angle between the radius and the fifth meta- 

 carpal bone, that of the abductor minimi digiti (which often permits 

 light to pass beneath it), and that of the palmar interosseous along 

 the first phalanx of the fifth finger. Separate fascicles of the pannic- 

 ulus can be detected either unattached (as is the rule) or continuous 

 with some of the fibrous trabecular already mentioned, or united 

 at one end to bone. 



Prominent among the markings are those of the nerves. The 

 following have been recognized : branches of the intercostal nerves, 

 of the superficial branches of the lumbar plexus* and of the inter- 

 costo-humeral, the internal cutaneous, the external cutaneous and 

 the median nerves. 



A study of these details has led me to form a good opinion of 

 their availability in describing families, genera and (sometimes) 

 species. 



When a specimen which is held for a moment before a moderately 

 bright light can be assigned in the majority of instances to its true 



* Since the superficial branches of the intercostal nerves are homologous with 

 those of the lumbar plexus they are all named for convenience the intercostals, — 

 the crural line is the lowest of the series. 



