14 STRATIOMID^E. 



stylo terminali brevissimo fingentes. Scutellum spinis duabus armatum. 



Alarum vense praebrachialis, pobrachialis, et intermediae non usque ad 



summum marginem interiorem descendentes. 



Body oblong-oval, black, of large or middle size, slightly pubescent. 

 Head semicircular. Epistoma convex, forming a keel. Ocelli 3. Eyes 

 green, often with purple bands. Peristoma small, circular. Proboscis 

 withdrawn. Labrum linear, rounded in front, covering the labium. 

 Lingua as long as the labium ? Maxillae very small, pointed, attached 

 with the labrum to the base of the labium. Palpi triarticulate, 

 diverging, seated on each side in front of the base of the labium; 

 joints cylindrical, of equal length ; third somewhat thickened. Labium 

 almost cylindrical. Antennas 7-8-jointed, porrect, contiguous at the 

 base, diverging, inclined upward; first joint cylindrical, longer than 

 the second ; second short, cyathiform ; third and all the following 

 forming a fusiform compressed pointed flagellum, which usually forms 

 an angle with the second joint ; eighth joint like a very short style. 

 Thorax oval ; scutellum semicircular, armed with 2 short spines. Wings 

 lanceolate, not pubescent, incumbent, parallel, not covering the sides 

 of the body. Alulae small, not covering the halteres. Abdomen oval, 

 5 -jointed, flat or but slightly convex, pubescent or almost bare, 

 often with yellow marks on each side, or partly green, which colour 

 prevails chiefly in the smaller species, when it commences beneath and 

 spreads thence over the sides of the back till it occupies the whole 

 surface. Legs slender. 



Male. Eyes contiguous ; facets larger on- the crown than in front. 

 Thorax hairy. 



Female. Eyes remote. Thorax almost bare. 



These flies feed on the honey of flowers, and appear in the 

 spring and in the summer on aquatic plants : their flight in 

 hot weather is very rapid but short, and they quickly return to 

 the spot whence they took wing. The larvae are aquatic, and 

 the metamorphose of S. Cham&leon has been often observed. 

 Its eggs from white become green, and then change to olive- 

 green ; they are arranged like tiles on a roof, one laid partly 

 over another, on the underside of the leaves of Alisma Plantago, 

 the water-plantain. The larva often remains suspended by its 

 radiated anus at the surface of the water, with its head down- 

 wards. Its ganglions are so near each other as to appear like a 

 string of beads. When it is disposed to sink to the bottom or to 

 descend, by bending the sides of its tail so as to form a concavity 

 it includes in them a bubble of air, in brilliancy resembling silver 

 or pearl, and then sinks with it by its own weight : when it 

 would return to the surface it is by means of this bubble. 

 If it moves upon the surface or horizontally, it bends its body 



