90 JOURNAL, BOMB AY NATURAL SIST. SOCIETY, Vol. XXU. 



other character found for their distinction. I may note also that alii 

 sorts of intergradations are found in the premaxillae and that it is often 

 almost impossible to decide whether a given specimen should be re- 

 ferred to one genus or the other by this character of the premaxillae.. 



A typical Nyctinomus has a long, smooth, flattened skull, with 

 a sinuate upper profile, aborted sagittal and reduced lambdoid 

 crests, open premaxillse, well spaced premolar region, palate 

 ending level with the last molar, and with normal, unreduced m^ 

 provided with four cusps and their connecting commissures. 

 Looked at from its inner side such a tooth shows (above the inter- 

 nal lobe) two well developed main cusps side by side, the posterior- 

 often (as in N. ivrougMoni) but little smaller than the anterior. 



Of the Indian species N. tragatus corresponds with this descrip- 

 tion in all respects, while, with the one exception of the pre- 

 maxillse, N. ivroughtoni and N. 'plicatvs are equally referable to- 

 the genus Nyctinomus. 



On the other hand typical species of the Mops group have the- 

 premaxillse closely united, the skull shortened, convex above, with 

 well developed sagittal and lambdoid crests, shortened premolar 

 region, the large p'* commonly almost or quite touching 

 the canine ; and, most important of all, a reduced m^, which is 

 compressed antero-posteriorly and has nearly or quite lost its 

 posterior cusp and commissures. 



Of Mops as thus defined the following are typical in all respects :: 

 mops, miarensis, demonstrator and midas, while various others may be 

 assigned to the genus on what I consider its most important char- 

 acter, the reduced m^, even when they diverge in other respects. 



P. 8. — February 1913. — Since writing the above I have been 

 able to make the more complete examination of the African 

 members of this group demanded for its proper arrangement intO' 

 genera. As I expected, the character of the structure of the last 

 upper molar (m^) proves to be far more important than that of the' 

 junction or separation of the premaxilla3, and may be used for the- 

 primary division of the group. The premaxilla3 and other charac- 

 ters are then available for a natural division into genera, of which 

 I should now recognize four, one, formed for Nyctinomtis tvroughtoni, 

 being new. Their characters may be briefly put as follows : — 



A. M^ complete, its ridges forming a Z of which the posterior- 

 limb or commissiire extends inwards as far as the- 

 anterior angle. 



a. Premaxillas separated ... ... Nyctinomus, Geoflf. 



b. Premaxillee united. 



a.^ Basi-occipital pits well defined, with 

 overhanging edges. 

 A prominent vertical projec- 

 tion on zygoma. ... Otomops, g. n. 



