A MONOGRAPH OF THE BATS OF NORTH AMERICA 115 



pectoi'Jilis. The lirst three Joints of tlie tail are (lis})]aye(l veiitard; 

 the remaiuiiig' Joints are displayed dorsad. The third nietacar])a], with 

 membrane palmad concealing contour at the proximal third. The 

 fourth metacarpal is crossed obliipiely by several nerves from the third, 

 to the fourth interspaces. 



Variafions. — The second scallop of the auricle may extend up a little 

 beyond the external basal ridge along the outer border, or it may be 

 divided into two parts by a notch at the ridge, and that portion of the 

 hem above the notch be revolute backward and reach tiie curve of the 

 tip, thus obliterating the emarginatiou. This was well seen in an old 

 individual in the National Museum, collected by Mr. Henshaw in the 

 Northwest territory. The external basal lobe may not have an involute 

 border. The tragus may be scarcely at all convex on the outer border 

 and nearly the same width throughout. Tlie margin of the interfemo- 

 ral membrane Joins the tail at the Joint between the terminal and the 

 adjoining vertebra instead of half along the last segment which is the 

 rule. The lobe at the end of the calcar is often absent, while the 

 post-calcaral lobe itself is rarely so. The tip of the tail in one imma- 

 ture specimen from Panama (3214 Cam.) was not exsert. 



For variations in lengths of the metacarpal bones, see measurements. 



The following notes have been taken from a number of examples col- 

 lected in California. The tragus is coarsely crenulate on the outer 

 border. The first scallop is markedly ccmvex. The second scallop is 

 Avide and conceals the posterior third of the external basal lobe, but 

 does not extend far up on the first scallop. The fleshy tip to the tail 

 occupies the greater part of the exsert portion. The face, ear, and 

 membranes are black. 



In three specimens the manal formula is subject to variations. It is 

 as follows : 



mm. mm. mm. 



Secoud interspace 2 1+ 2 



Third iuterspace 1 84^ 11 13 



Fourtli interspace 31 35 30 



Forearm 44 42 44 



Slcull. — The sagittal temporal crest is well developed over the me. 

 sencephalon ; of equal height with the occipital crest, the two forming 

 a conspicuous elevation at the back of the skull. The region of the 

 mesencephalon equals three and one-half times the length of the skull. 

 The region of the proeucephalon is flat and retains one foramen. The 

 vertex of the face with a low nasal eminence for the anterior half. The 

 posterior half is depressed, and is continuous with the anterior two- 

 thirds of the sagitta. A shallow fossa is seen on the maxilla at the 

 side of the nasal eminence. The frontomaxillary region is moderately 

 inflated. A distinct projecting lamina overlies the lachrymal bone. 

 The inner wall of the orbit is nearly flat, while its upper border is in- 

 flated. The infra-orbital foranuMi is large, subcoidate, and defined 

 inferiorly. The depression in the region of the foramen extends be- 



