45 



tion as in Lasiurua, but which appear nevertheless to have the otlier 

 parts as in the more ordinary Bats. 



One of these — Vesp. pallidus, Le Conte, — the writer says, has 

 only four incisors in the lower javv, — altogether an anomalous cha- 

 racter, if not due to some accidental cause. 



The other species is the Vesp. crepuscularis of the šame naturalist 

 (F. creeks, F. Cuv.), which, vvhile possessing only two iipper incisors, 

 precisely as in Lasiurus, has yet all the other characters similar to 

 those of Vesp. Carolinensis, — a species clearly appertaiuing to that 

 division of the genus Scotophilus which constitutes Section b. of the 

 genus Vesperugo of MM. Keyserling and Blasius. 



It would appear from this that the number and form of the inci- 

 sors in the upper jaw do not furnish a very vaU\able generic cha- 

 racter ; and when we find another species from India, not only dif- 

 ferent in its forms from Lasiurus and Ni/cticejus (so called), but 

 also differing from the above-mentioned Vesp. crepuscularis in all 

 respects save in the upper incisors, which are similar, we are quite 

 justified in regarding this as a character of subordinate value in the 

 arrangement of this difficult group of animals, 



The Indian species to which I allude is referable, as far as external 

 form is concerned, to that section of the genus Vespertilio which has 

 been called Cappacinius by Prince Charles Lucien Bonaparte, and 

 Trilatitius by Dr. Gray. It is closely affined to the Vesp. Tasma- 

 nensis of the latter zoologist, and may perhaps prove identical with it. 



Besides the species given in this Monograph, there are several 

 others differing materially from them, and from each other, but 

 which have the tail-membrane hairy. As instances, may be cited 

 Vesp. noctivagans, Le Conte {V. pulverulentus, Temm.), Lasiurus 

 Pearsonii, Horsf. * (closely affined to the Vesp. emarginatus of the 

 contiuent of Europe), and Vesp. suillus, Temm., called Murina 

 suillus by Dr. Gray, and Noctilinia Lasyura by Mr. Hodgsou. 



From this it mušt be evident that this character is only of generic 

 value when associated with others of greater constancy, and it is only 

 by the characters taken collectively that the groups can be truthfuUy 

 defined. 



The form of the head, the muzzle, and the uostrils, of the ears and 

 the tragi, the extent of the membrane in reference to the hinder ex- 

 tremities, the ąuality and distribution of the fur, the number and 

 form of the upper incisors, and more than all, the general conforma- 

 tion of the cranium, supply the means by which the Lasiuri may be 

 recognized and associated. 



* In alluding to this species, I may menticn, that it is the Vesp. emarginatus 

 of Continental writers to vvhich I refer, — a well-uiarked species very similar in ap- 

 pearance to Lasiurus Pearsonii, but not more than half the size, and yiith. less 

 hair on the interfemoral membrane. The so-called British species ie, I believe, 

 no other than Fesp. mystacinus. 



