A MONOGRAPH OF THE BATS OF NORTH AMERICA. 6 



the lower extremity, aud a hypotlietical line drawn downward from the 

 elbow and intersectiug the free margin of the membrane, is the endo- 

 patagium. 



The boundary at the elbow is often fixed by the vertical terminal 

 branch of the triceps fascide system. Tlie subordinate lines (probably 

 platysmal in origin) in the endopatagium incline obliquely either to- 

 ward the humerus or the trunk. 



The part of the wing membrane which is limited by the line at the 

 elbow as above given, by the forearm, and the fifth metacarpal bone 

 and phalanges, is the mesopatagium.* Within the mesopatagium the 

 subordinate lines incline either toward the forearm or the manus. 



The part of the wing membrane limited to the manus becomes the 

 ectopatagium (dactylo-patagium). Tlie subdivisions of the ectopatagium 

 are the first, second, third, and fourth interspaces. These are named 

 from the poUex toward the quintus. The series of bones which is em- 

 braced in the metacarpal and phalangeal lines being conspicuous in 

 the bat, it is desirable to possess a name in referring to each series 

 taken as a whole. The name digit will be used for the rod of segments 

 embracing the metacarjial element. The nerve which appears at the 

 anterior margin of a digit becomes predigital, and that of the posterior 

 margin, postdigital. 



The cartilaginous tip to the terminal bony phalanx, respectively, of 

 the third, fourth, and fifth fingers might receive the name of the third 

 phalanx when three phalanges are present, and of the fourth phalanx 

 when four phalanges are present.! The shapes of the terminal pha 

 langes are of interest and some of these will be described. 



I have examined a sufficient number of genera to suggest that an 

 account of the markings of the wing membranes and of the shapes of 

 the terminal phalanges enter into all discriminating studies. 



The division of the wing membrane into the parts endopatagium, 

 mesopatagium and ectopatagium is sustained by what is observed in 

 Taphozous mauritianus, since in this species the endopatagium is of a 

 dark color while the rest of the membrane is white, excepting the extreme 

 tip of the end of the third finger. Xow when the animal is at rest the 

 surfaces above named are those only which are exposed to the light. 

 In all young bats which cling to the mother, without exposing any other 

 portions of the membrane than those named, it is evident that for a 

 long period the endopatagium has functions which are not exacted of 

 the rest of the wing membrane, and in consequence, in my judgment, 

 it is easy to see how this portion of tlie wing expanse shoukl be dis- 

 tinguished from those portions which are used only in flight. 



*The euclopatagiuni and mesopatagium are together the same as plagiopatagium 

 of Kolenati. (Beitr. z. Naturgcsch. derEurop. Chir., Dresden, 1857.) 



tit must be acknowlcdgod that the study of the embryos does not ronfirm the 

 statement liero made. In a word, the segmentation of the cartilage from the shaft of 

 the bony jihalaux remains a probability only. 



