I. STRATIOMYIDiE 55 



British, Of the 200 Palffiarctic species about 160 belong to four genera 

 {Nemotelais, Oxycera, Stratiomys, and Odontomyia), and these four genera 

 are well represented in Britain. Very few, if any, species show any 

 marked powers of flight, and none are known to hover ; * they occur 

 rather sluggishly on flowers or may be swept up in low herbage {Nemotelus, 

 Oxycera); the Sargince with their brilliant metallic green coloring love 

 to rest on the leaves of shrubs in the bright sunlight, and many of them 

 are then very active when alarmed; the males of Nemotelus sometimes engage 

 in an aerial dance over marshy ground, while the males of CJiorisoj^s tibialis 

 may often be seen dancing in small companies beneath the branches of trees. 



The metamorphoses of a considerable number of species are well 

 known, and they prove the close relationship of Pachygastcr, Savfjus, Bcris, 

 Xylomyia, etc. The eggs are laid on plants at the margin of water or 

 even on the surface of the water, and the larvte are carnivorous or live on 

 decaying vegetable matter in water or in the earth; the young larvae 

 resemble the old ones, and in many species the larvic are capable of 

 remarkable elongation, which has given them the name of " rat-tailed 

 maggots," a name also used for the larvae of some species of Eristalinoi, 

 Further details are given under various genera, but my remarks are only 

 compilations as I have no knowledge of the subject myself. 



Arrangement: — The Pahearctic species of Ititraimnyidcc readily fall 

 into aljout six subfamilies, of which the Berinm and Xylomyina'. show a 

 distinct tendency towards the Leijtida: in the more numerous visible 

 segments of the elongate parallel- sided abdomen, in the more elongate 

 cubital fork, and in the longer hexagonal discal cell ; these two subfamilies 

 may therefore be placed last (next to the Leptida^), the Xylomyiiia: being 

 last of all because of the spurred tibia? and especially because of the 

 preef urea = (common stalk of the radial and cubital veins) originating long 

 before the base of the discal cell, though the armed scutellum of Canomyia, 

 in the Leptida: might indicate some relationship to the Berina: ; of the 

 remaining subfamilies the very distinct Pachygastrinw are usually placed 

 first, though the presence of only two veinlets emerging from the discal cell, 

 the long portion of the upper branch of the postical vein which forms the lower 

 boundary of the discal cell, and the short anal cell would seem to indicate 

 relationship to the Berinw ; on the other hand, the long-bodied species of 

 Sargus are more probably correctly placed next to the Berina?, as is shown 

 by the increasing cubital fork, etc. ; between the Paxhygastrinm and the 

 Sarginm come the Clitellarince and Stratiomyince, which might well form only 

 one subfamily as they are separated only by the weak character of the 

 presence or absence of the small cross-vein. A sequence is thus arrived 

 at from the small short-bodied unicolorous species of Pachygaster on to 

 Nemotelus nigrimis and the rest of the Clitellarince, and thence through 

 Pycnomalla to the Stratiomyince, and through unicolorous Odontomyice to 

 the short-bodied Sarginoi (Mierochrysa, etc.), and thence through the long- 

 bodied Sarcjince to the Berince and JCylomyince. Other affinities may exist 

 in the bright metallic coloring of the Sargince and most of the Berinm ; 

 in the short rounded third antennal joint and the long arista of Pachy- 

 gastrince and Sargince, in the antennse of the aberrant Oxycera tenuicornis 

 and the Berince, etc., etc. 



* I consider the word '•' hover " to indicate the apparently motionless poise in the air of an individual speci- 

 men while the wings are rapidly vibrating, but " dance " to indicate the rhythmical movement in the air of a 

 small group of specimens. 



