MYOTIS 185 



External characters. — Smallest of the large-footed European 

 species. General form less slender and delicate than in M. 

 mystacinun, the tail and legs relatively shorter. Ear rather 

 short, extending, when laid forward, about to tip of muzzle ; 

 anterior border faintly and evenly convex from basal lobe to 

 narrowly rounded-off tip ; posterior border with shallow though 

 evident concavity above ; antitragus small and ill-defined ; tragus 

 about half as high as conch, its greatest width contained three 

 times in length of anterior border, the posterior border 

 moderately and evenly convex, the anterior border nearly 

 straight, the tip rather blunt ; posterior basal lobe relatively 

 large and well defined. Wing slightly broader than in 31. mi/sta- 

 cinus, the three main metacarpals evidently graduated from 

 third to fifth, the third very slightly shorter than forearm ; 

 membrane inserted at middle of metatarsus. Foot large, 

 appreciably more than half as long as tibia ; calcar slender, 

 very long, without keel on posterior border and with slight 

 terminal lobe, its length fully double that of free border of 

 interfemoral membrane. Tail about as long as body without 

 head, the terminal vertebra free from membrane except for an 

 exceedingly narrow strip extending outward along each side. 



Fur and colour. — Fur slightly shorter and more dense than 

 that of 31. mystac'mus, but with no peculiarities of distribution 

 except that it tends to spread farther outward along dorsal 

 surface of interfemoral membrane ; free border of urojiatagium 

 not fringed, but a slight fringe is usually present along basal 

 half of calcar. Colour above essentially as in ilf. nattereri, 

 though usually inclining more definitely toward wood-brown ; 

 underparts buffy grey visually less contrasted than in 31. nattereri, 

 though sometimes pale enough to produce a distinct line of 

 demarcation along sides of neck. Muzzle and cheeks dusky. 

 Membranes and ears an indefinite brown. 



Skull. — The skull of Myotis dauhentonii is smaller tlian that 

 of any other European species except 31. niystacimifi. From this 

 it is immediately distinguishable by its noticeably greater breadth 

 both of rostrum, palate and brain-case, by the relatively lower 

 occipital region, and relatively deeper rostrum. Posterior exten- 

 sion of palate short and broad, the width just behind molars 

 greater than length to tip of hamular ; median projection angular, 

 seldom forming a distinct spine. Greatest breadth of brain-case 

 slightly though appreciably more than greatest length of skull. 

 Mandible with coronoid process low, scarcely rising above level 

 of condyle. 



Teeth. — Teeth relatively smaller than those of 3lyotiS mysta- 

 cinus, a difference particularly noticeable in the crown areas of 

 the first and second upper molars. Upper incisors as in mystacinus, 

 but with cingulum less developed. Lower incisors very slightly 

 imbricated, tlie form of the row vacillating between (J-shaped 

 and broadly V-shaped, the cusps as in 31. mystacinus but less 



