Zoological Society. 217 



In the type of that genus {Megacephala senegalemis, Latr., Dej., 

 Cic. niegalocephala, Fabr.), an apterous species from Senegal, the 

 right mandible of the male has two large, nearly equal-sized, acute 

 teeth in the middle of the inner margin, the extremity being hooked 

 and very acute ; there is also a small tooth at the base of the large, 

 broad, compound basal tooth. The left mandible is nearly similar, ex- 

 cept that the two teeth in the middle of the inner margin are unequal 

 in size, the upper one being the smaller of the two. The figure of ths 

 jaws of this species, given in the Crochard edition of the Animal 

 Kingdom (Ins. pi. 16. f. 2 a), is very incorrect, being apparently 

 reversed. The dentition of the female is almost identical with that 

 of the male. In the allied bat -winged African species, Megacephala 

 4-signata, Dej., from Senegal, the toothing of the mandibles is simi- 

 larly arranged, but the two teeth in the middle of the inner margin, 

 in both sexes, are broad and obliquely truncate. In the male of 

 M. euphratica (which has recently been observed to extend from 

 Spain to India), the teeth are nearly as in M. senegalensis, except 

 that the subapical tooth of the left mandible is considerably smaller. 

 But in the species lately received from the north-west of Australasia 

 (Af. Aiistralasice, Hope), we find a different arrangement as well as 

 number in the teeth, the right mandible having three teeth in the 

 middle of the inner margin (exclusive of the small tooth* at the base 

 of the upper side of the large compound basal tooth), the upper one 

 small, the middle one very small, and lower one large, all being acute. 

 The left mandible has also three teeth in the same position, — the 

 upper one very small, and the middle and lower one large and nearly 

 equal in size. 



On turning to the New-World species of the genus, we find four 

 variations in the dentition of the mandibles ; the group of pale spe- 

 cies typified by 31. eequinoctialis, Dej. {bifasciata, BruUe), corre- 

 sponds almost identically in the dentition of both sexes with the old 

 type (3/. senegalensis), as described above, the right mandible having 

 two equal-sized large acute teeth in the middle of the inner margin, 

 and the left one also two, the upper one being very small. For this 

 group I have proposed the subgeneric name of Ammosia, in allu- 

 sion to their habits, which differ materially from those of the other 

 species. 



A black-coloured species from South America {M. sejmlchralis, 

 Fabr., M. variolosa, Dej .) differs from the Ammosics in the left man- 

 dible, while the inner margin has only one tooth in the middle, of 

 considerable size, and exhibiting on its \inder side a minute tooth, 

 being all that remains of the large middle tooth of the left mandible 

 of the Ammosice. This species is the type of Mr. Hope's subgenus 

 Anaira. 



Another very fine Brazilian species {M. testudinea, Klug) differs 

 in the dentition of the sexes in a more striking manner than any of 



* This small tooth exists in all the species, and in both sexes ; and as it appears 

 to form part of the great basal tooth, I have omitted noticing it iu the descriptions 

 given in this paper. 



Ann. &- Mag. N. Hist. Ser. 2. Vol. xii. 15 



