Descriptions of British Diptera. 145 



of tail fourteen inches and a-half. Inhabits the Island of Ceylon, 

 and does not appear to have been yet described. 



It is named in honour of the individual who formed the genus, 

 and though the form and mode of arrangement of the scales are dif- 

 ferent to those of Chrysopelea ornata, yet it is clearly a species of the 

 same genus. As far as regards the character of the scales and their 

 mode of distribution it is nearly allied to the genus Bucephalus, as 

 described by me in one of the numbers of the Zoological Journal. 



2. Chrysopelea Capensis — Ch. supra viridi-ccerulea, infra antice 

 viridis, viridi-flavo umbrata, postice viridi-ccerulea. 



Abdominal plates 216. Subcaudal scales 109. 



Above greenish blue, verging towards a light slate hue ; head tinted 

 with purple ; anterior part of belly light green, mottled with green- 

 ish yellow, posterior part the same colour as back ; scales large, sub- 

 ovate, and disposed in oblique rows, as in the Chrysopelea ornata, all 

 of them, as well as the abdominal plates and subcaudal scales, with 

 a shining metallic lustre; eyes brown. Length from nose to anus two 

 feet eight inches, from anus to tip of tail eleven inches. The three 

 species probably all belong to that class of snakes which generally 

 resort to trees to obtain their food, — at least the last described was 

 killed when turned round the branch of a high shrub, near to the 

 mouth of the Orange river. 



As has already been remarked, the scales of the present species 

 are arranged as in the one which Mr Boie selected for the type of the 

 genus. Their forms also approximate to those observed in it, and thus 

 differ in both respects from the Chrysopelea Boieii, found in Ceylon. 



V. — Characters and Descriptions of the Dipterous Insects indige- 

 nous to Britain. By James Duncan, M. W. S., &c. &c. 

 (In the following series of papers it is proposed to give a list of 

 the Dipterous insects indigenous to Britain, with the Generic cha- 

 racters, Specific descriptions, and Localities, with as much accuracy 

 as it is possible from the materials in the possession of the author. 

 This singular and interesting tribe of insects has been hither- 

 to comparatively neglected by British entomologists, but several 

 valuable continental publications have been devoted to them, and 

 in drawing up the characters and descriptions, Mr Duncan has chiefly 

 made use of Meigen's Europaischen Zrveiflugeligen Insecten, and Mac- 

 quart's Insectes Dipteres du nord de la France, works of great pre- 

 cision and minute accuracy. — We have already to offer our acknow- 

 ledgments to several gentlemen, for communications relative to the 



