378 Zoological Society : — 



The lower jaw so closely resembles that of the generality of the 

 Vespertilionidce, that I consider it only necessary to state that it 

 appears to resemble the same part in Scot. Noctula as closely as in 

 any other species, differing only in having the coronoid process a little 

 more elevated. 



Commencing the description of the teeth themselves with the 

 upper incisors, I find them to be two in number, short and conical, 

 and furnished with a distinct cinguluMy which passes into a point on 

 the hinder side of the tooth, well defined in some species, but scarcely 

 observable in others. In those in which it does occur, it constitutes 

 a peculiarity quite distinct from the bifid incisors of some species, 

 such as the Barhastelle, where the cingulum is left entire, and the 

 apex of the tooth appears as if cleft. 



The canines are somewhat shorter and relatively a little stouter 

 than in Vespertilio and Plecotus, and also shorter but not stouter 

 than in Scotophilus. The next tooth, the only premolar in the 

 upper jaw, and the following three true molars, have the form and 

 proportions so usual in the VespertilionidcBy that they require no 

 special notice, excepting to state that the posterior one is a little 

 smaller than is generally observable. 



In describing the teeth of the lower jaw, two errors which have been 

 made respecting their number require correction. Dr. Leach states 

 that the lower incisors are six in number, and M. Temminck, de- 

 scribing afterwards from the same specimen, could find but four. 

 After diligently examining a considerable number of skulls, I have 

 satisfied myself that the account given by Dr. Leach is correct, for 

 in no instance can I discover less than six lower incisors ; but in two 

 examples the outer one on each side is wholly hidden by the one 

 next to it, so that unless the skull be carefully cleared of the invest- 

 ing membranes, it would be extremely difficult to see more than four 

 of these teeth ; hence has probably arisen the error. 



They are cylindrical at the base, and for a considerable part of 

 their length ; but expand into flattened fan-shaped summits, having 

 three lobes or points. The canines are of the usual form, and are 

 not, as has been stated, furnished with a posterior lobe or spur. 

 What has been mistaken for a part of the canine, is in fact a small 

 and pointed premolar, placed so close behind it as to seem continu- 

 ous with it. On instituting an examination of the canines, and com- 

 paring them with those of other species, I find that the cingulum is 

 not so much developed posteriorly as in many others. In the com- 

 mon Noctulcy for instance, although the canine presents only a mere 

 trace of thickening of the base anteriorly, it nevertheless passes into 

 a small but distinct spur or point behind. The small anomalous 

 premolar alluded to is situated in the same line with the teeth, be- 

 tween which it is placed in such a manner as to be equally visible 

 from within or without. Its form is conical. The next tooth is 

 also regularly conical, and furnished with a broad basal collar or 

 cingulum; after this come the three true molars, presenting the 

 form common to all the Vespertilionidce. 



The dentition of the genus may be given as follows ; and as that 



