Mr. R. F. Tomes on the species of Lasiurus. 215 



marks, well relieved by the dark blackish -brown background ; 

 underside covered with whitish pubescent hairs ; abdomen down the 

 middle nearly bare of hairs ; legs with cinereous pubescence. 



14. Agelasta Newmanni, n. s, 



A. ccBindescenti-cinerea, pubescens ; thorace nigro transversim uni- 

 fasciato, efytris nigro bifasciatis et maculatis. 



Long. lin. 6^. 



Hub. Borneo (Sarawak) {Coll. A. R. Wallace). 



The greater part of the insect covered with a bluish-grey pubes- 

 cence ; the head with some black marks ; the autennse black, the five 

 basal joints bluish-grey at the base ; thorax above with a transverse 

 black baud, the front and hind margins running into the greyish 

 pubescent part. Scutellum covered with grey jjubescence. Elytra 

 with two transverse black bands, one before, the other behind the 

 middle ; the parts clothed with greyish pubescence have a few black 

 spots, those between the bands arranged transversely, those at the 

 apex triangularly. 



February 24, 1857.— Dr. Gray, F.R.S., in the Chair. 



A Monograph of the Genus Lasiurus. 

 By Robert F. Tomes, Esq. 



The object of the present memoir is rather to enumerate and de- 

 scribe all the species at present arranged under the above name, than 

 to enter into the claims of the group to be considered as a distinct 

 genus. 



An attempt is also made to give a tolerably correct synonymy ; 

 but there are so many descriptions which appear to refer to varieties 

 only, as to render this part of the work by no means easy, and not 

 altogether satisfactory. Attached to the account given of the first 

 species on the list — Lasiurus novehoracensis — will be seen a rather 

 voluminous list of synonyms ; and it may appear as if too little regard 

 had been paid to the labours of other writers, iu thus reducing to one 

 species what has by them been considered as constituting at least 

 six. But iu the examination of a large number of examples, I have 

 felt myself quite unable to come to any other conclusion than the 

 one here given. The various descriptions apply to the same species 

 under the influence of the climate of different degrees of latitude. 

 Thus the Vespertilio novehoracensis answers well to the account 

 given of it in its proper localitj^ ; but as we proceed southward, we 

 find that a Bat occurs, having precisely the same form and size, but 

 differing somewhat in the colouring of the fur ; and this difference 

 continues to increase until we reach the tropical parts of America, 

 where a bright ferruginous colour completely supersedes the original 

 hoary-brown, or, as it might not improperly be called, roan-colour. 



At various localities it has been met with by travellers, and the 

 colour of the fur varying iu most of them, has given rise to the 



