128 SYRPHID.E. 



1 (2) Entirely black and elongate species, 



more' than '20 mm. in length ; an tenure 

 and legs bl.tck, but the latter some- 

 times of a reddish colour in the male ; 

 abdomen elongate, the second seg- 

 ment produced on each side, very 

 thinly punctate ; third antennal joint 

 half as long as the first mytlits, ?p. n. 



2 (1) Less elongate species, not more than 



18 mm. in length, the abdomen 

 broader than the thorax at the base 

 and conical, its second segment always 

 simple ; not entirely black, the abdo- 

 men, head, antennae, or legs being red 

 or yellow; third antennal joint about 

 as long as the first. 



3 (4) Abdomen black; head, antennae, and 



legs wholly red erytlirocephalus, sp. n. 



4 (*3) Abdomen yellow or red ; antennae 



black ; head black or with the face 

 alone yellow. 



5 (8) Legs wholly black: face yellow; first 



and second antennal joints clothed 

 with rather long hair ; rather pro- 

 minent species of larger size. 



6 (7) Abdomen yellow ; Eastern species .... luteiventris, sp. n. 



7 (6) Abdomen red; Western species erytltro*, Bezzi. 



8 (5) Legs wholly or mostly red or yellow ; 



face black ; first and second antennal 

 joints almost bare ; smaller and less 

 pilose species. 



9 (10) Hind legs jjartly black ; the two first 



antennal joints of a dark reddish 



colour cethiopicus, Ilond. 



10 (9) Hind legs entirely red or yellow ; 



antennae entirely black. 



11 (12) Abdomen and legs dark red ; wings 



with a uniform bluish-black tinge ; 

 trochanters and pleurae black ; arista 

 reddish inermis, Loew. 



12 (11) Abdomen and legs pale yellowish red ; 



wings infuscated along the veins 

 alone ; trochanters yellowish ; pleurae 

 sometimes spotted with yellow ; arista 

 black palliduf, sp. n. 



135. Microdon mydas, sp. n. 



d $ Length of the body in the male 19 mm. ; in the female 

 21 mm., excluding in each case the antennae, which are 5 mm. 

 long. 



A wonderful dull black species of considnrable size, resembling a 

 Mydas, and exhibiting some of the characters of the preceding 

 group, with which it forms a connecting-link. 



The two sexes show remarkable differences in coloration. T will 



