216 Zoological Society. 



and fourth graduated ; the first, third, fourth, fifth, sixth and seventh 

 quills are emarginate on the outer web. 



Tail of twelve graduated feathers, the two outer being the short- 

 est ; under-coverts are long. 



Legs long, the tarsus |-ths of an inch ; the outer toe longer than 

 the inner. Hallux very strong, and as long as the outer toe, with a 

 large pad beneath the base, its claw the largest ; the tarsus is co- 

 vered with seven scales in front and one entire behind ; two large 

 scales lie across the front of the foot ; the claws are curved and 

 sharp. 



Contents of stomach a mass of insect exuviae. 



Colours : all above dull green, tinged with ash, light brown towards 

 the end of the tail and quills, which are lighter on the edges. Two- 

 thirds of the front breadth of the neck, round the eye, the breast, 

 belly and thighs (except a chestnut spot on the hallux) are silver- 

 white ; there is, besides, a remarkable spot on the neck, of a brown 

 colour, as if the white feathers had been deranged, showing the 

 roots of a different colour. Bill ash-brown or horn-colour, the 

 lower jaw lighter, and both lighter on the edges, as also are the 

 legs and claws of the same colour ; forehead of a fine chestnut ; 

 crown of olive-brown. 



June 24, 1851.— J. E. Gray, Esq., F.R.S., Vice-President, in the 



Chair. 



1. Observations on the Dentition of the Tiger Beetles. 

 By J. 0. "Westw^ood, Pres. E.S., F.L.S. etc. 



Mr. Westwood directed the attention of the meeting to the neces- 

 sity which existed of a more precise examination and description of 

 the diversity in the dentition of the mandibles of insects, especially 

 Hymenoptera and Coleoptera, than had hitherto been bestowed 

 thereon. In the higher orders of animals so much importance had 

 been given to this character, that it was remarkable that, in general, 

 entomologists contented themselves with examining, describing, and 

 figuring a single mandible as affording a sufficient diagnosis of the 

 structure of both of the mandibles, overlooking the necessary result 

 which arose from the circumstance of the horizontal instead of per- 

 pendicular action of these organs in insects, and the variation in the 

 position of the teeth which such action must necessarily induce. In 

 general, indeed, the teeth of the mandibles were not greatly developed, 

 and there was a general similarity between the two jaws ; but when 

 these organs are of an increased size, and especially when the extre- 

 mity of one jaw laps over that of the opposite one, a diversity in the 

 dentition will necessarily exist. It was likewise necessary to examine 

 the mandibles of both sexes of a species, as it occasionally happened 

 that there was considerable difference in their dentition. These ob- 

 servations were illustrated by the case of the Tiger Beetles {Cicinde- 

 lidce), which offered a much greater range of diversity in their denti- 

 tion than had hitherto been supposed. It was chiefly to the genus 

 Megacephala that Mr. Westwood directed the attention of the 

 members. 



