Fossil Bats 107 



us; V7212, distal end of right humerus; VI 603, complete left humerus; 

 V72 13-72 16, V7231, proximal portions of left humeri; V7230, distal end 

 of left humerus, V7217, one right and one left femur; Stratum 

 unknown-V7208, nearly complete edentulous right mandible; V7210, 

 complete right humerus; V7232, nearly complete left humerus; V7233, 

 distal end of left humerus. 



Recent distribution. — Nycticeius humeralis occurs throughout the 

 eastern United States and along the Gulf Coast as far south as the state 

 of Veracruz, Mexico. It is found throughout Florida and is one of the 

 most common bats of south Florida (Jennings 1958), specimens having 

 been taken as far south as Collier and Dade counties. 



Fossil record.— The specimens of N. humeralis from Vero represent 

 the first fossil record of the evening bat from Florida. The two speci- 

 mens from Stratum 2 constitute the second record of N. humeralis from 

 the Pleistocene of North America, the other occurrence being in Baker 

 Bluff Cave in northeastern Tennessee (Guilday et al. 1978). 



Description and comparisons, — The three mandibles referred to N. 

 humeralis can be readily distinguished from Myotis and Plecotus by the 

 presence of only two premolars, from Pipistrellus by their larger size, 

 and from Eptesicus, Eumops, and Lasiurus intermedius by their consid- 

 erably smaller size. The mandibles are generally similar in size to the 

 two smaller species of Lasiurus, but they differ from them in possessing 

 a longer, more slender mandibular ramus and a larger coronoid process, 

 and in lacking a deep cleft between the paraconid and metaconid on all 

 molars. The fossils can be differentiated from Tadarida brasiliensis by 

 smaller size, presence of a single-rooted rather than a double-rooted P3, 

 strong rounded coronoid process, deep masseteric fossa, small entoco- 

 nids on molars, and relatively large incisors (the incisors are small and 

 compressed in Tadarida). The characters of these three mandibles, 

 including size, length and depth of ramus, shape of coronoid process 

 and masseteric fossa, and morphology of the dentition, agree closely 

 with specimens of N. humeralis (see measurements in Table 1). 



Twelve humeri from Vero are referable to Nycticeius humeralis. 

 They can be separated readily from Eptesicus and Eumops by their 

 smaller size, and from Tadarida and all species of Lasiurus by the 

 hemispherical humeral head and reduced distal spinous process. Based 

 on a number of characters, the humeri can easily be narrowed down to 

 Myotis, Pipistrellus, and Nycticeius. The most reliable character on the 

 proximal end of the humerus for separating the fossils from Myotis and 

 Pipistrellus is the more prominent medial ridge extending ventrally from 

 the lesser tuberosity and producing a larger fossa or concavity for the 

 origin of the lateral head of the triceps muscle. In a posterior view of the 

 proximal end, that portion of the humerus medial to the pectoral ridge 



