THE FAMILIES AND GENEBA OF BATS. 163 



Number of form*. -Three species are known, Ardrops nlchoTlsi 

 (Thomas), A. montserratensis (Thomas), and .1. lucim (Miller). 

 Characters. — Dental formula : 



-2 3. 1. --34567.2-2 1-1 2-2 3-3 on 



12-. 1.-2-4 5 6 7 '2-2' 1-1'^ 2-2' 3^3" 



Upper incisors proportioned about as in Artibeus and forming a 

 straight line between canines, the outer rising barely to level of cin- 

 gulum of canine, its crown broader than long, deeply grooved on 

 anterior face, its cutting edge entire and with faintly indicated 

 cusp, but scarcely oblique, the inner about twice as high as outer, but 

 with its length nearly equal to its height, its posterior surface con- 

 cave, its cutting edge rising to a blunt main cusp on inner side and 

 sometimes showing a rudimentary second cusp on outer side. Lower 

 incisors subequal, smaller than upper, the crowns projecting conspic- 

 uously forward beyond roots, the anterior surface oblique, higher 

 than wide, deeply grooved, the groove passing through cutting edge 

 and short posterior surface. Canines stout, scarcely higher than 

 large premolars (pm* and pmA, the lower with well developed 

 postero-external talon, this slightly indicated in upper. Anterior 

 upper premolar (pm z ) essentially like canine, but not as high, 

 and with better developed postero-external cingulum • cusp. Pos- 

 terior upper premolar (pm*)- about as high as canine, but with 

 longer base and with a conspicuous, deep, postero-internal con- 

 cavity for reception of protoconid of first lower molar; posterior 

 cutting edge with large secondary cusp near middle in addition 

 to the basal talon. Anterior lower premolar (pm 2 ) essentially 

 like anterior upper premolar. Posterior lower premolar (pm 4 ) 

 more nearly resembling lower canine and with similar large 

 postero-external talon, but the length of crown greater in propor- 

 tion to the height, and the shaft thicker basally. Upper niolars as 

 in Artibeus except that hypocone of m * is relatively larger and 

 more distinct from protocone, which it nearly equals in height ; m 3 

 about as large as metacone of m 2 , its surface concave, with a minute 

 inner cusp and two outer cusps, one of the latter situated distinctly 

 inward from the cingulum. A distinct though small median cusp 

 on outer side of m 2 is possibly a rudimentary mesostyle ; outer 

 cingulum obsolete, but inner unusually well developed, that of m 1 

 passing around anterior base of paracone. First lower molar dif- 

 fering noticeably from that of Artibeus in the relatively much larger 

 and higher protoconid, the inner side of which is provided with a 

 high ridge which obliterates metaconid and extends backward to 

 beyond middle of crown; entoconid high and distinct, relatively 

 much larger than in Artibeus. Second lower molar more nearly 

 resembling that of Artibeus, but with, the protoconid, metaconid, and 



