NORTH AMERICAN BATS. 



Dentition. 



5 12 15 



Molars . Canines — Incisors — Canines — . Molars — ==30 teeth. 



5 ■ 1 4 1 5 



Upper Jaw. — Superior incisors converge but do not touch. 

 The first premolar is very small, but not hidden ; the second has 

 a sharp, well defined internal cusp. The internal cusp of the third 

 upper molar has a posterior prolongation ; last molar large. 



Loiccr Jaxo. — The incisors are very small, l)ilobed and cro^vded. 

 The canines are slender, with an internal cusp, which does not 

 meet its fellow in the middle line. Two premolars of nearly 

 equal size, unicuspid, the posterior being a little the larger. The 

 remaining three molars are in nowise peculiar. 



A singular confusion has always existed in the efforts of 

 naturalists to accurately determine the forms of the Molossoid 

 group of the Noctilionid®. 



The names of Ve>fpertiUo, Molos^iit^, D>/sopes, Dinops and Kijcti- 

 nomus, have been applied almost indiscriminately to the different 

 species. Geof. St. Ililaire established the genus Jllolossua, in 

 1805, in Ann. du Mus. VI, 150. In 1814, he founded the genus 

 Nyclinomus in the " Description de I'Egypte." As far as my ob- 

 servation has been extended, it is among these two genera that 

 the different s})ecics can be properly grouped, excepting j)er- 

 haps the form Cheiromeles, Horsf Jlolos.^uf; is an Amei'icau 

 genus. Nydinomiis has an extensive distribution, being found iu 

 Africa, Australia, and America. Peters, in " Reise nach JNIo- 

 zamlwcpie," has described two African species under the names of 

 Dysopc^ hrachypterus and limbatus, but the figured skulls and 

 heads correspond exactly to those of Nyctinomus. Tomes, while 

 adverse to the separation, states that if separated, MoloHsua 

 australis, Gould, from Australia, belongs to Nyctinomus. Hors- 

 field's elaborate and sagacious researches in Asia have brought 

 to light iV. tenuis; and finally, Is. St. Hilaire noticed as early 

 as 1824 (Ann. des Sc. Nat., April, 1824), the prevalence of the 

 genus in America. 



Nyctinomus can readily be distinguished from Molossus by the 

 following characters : — 



Molossus. Superior incisors converge and touch. Molars 

 four iu upper jaw ; internal cusp of third molar not prolonged 



