164 



THE BRITISH NATURALIST. 



[July 



a blue abdomen, the first and second segments being of a reddish 

 tawny. 



Sargus infuscatus, male with a green, female with a blue abdomen. 



Oxycera rara, pardalina, and formosa, females have yellow stripes on 

 the thorax, which the males have not. 



Oxycera Morisii and longicornis, females have yellow spots on the 

 head, which the males have not. 



(Oxycera analis and terminata, both sexes of same colour.) 



Oxycera trilineata and muscaria, females have yellow collars, which 

 the males have not. 



Nemotelus uliginosus and pantherinum, males have a large white 

 patch on the abdomen, which the females have not. 



Odontomyia argentata, male is clothed with silvery down on the 

 abdomen, the female is not. 



Chrysops caecutiens, male black, and with very black wings, female 

 with a large yellow patch on the abdomen, and with lighter wings. 



Thereva anilis, male clothed with white down on the abdomen, the 

 female is not. 



'Atherix ibis, male is fulvous on the abdomen, the female is not. 



Empis livida, male has dark, female light, wings. 



Platypeza rufa, male has dark, female has light, wings. 



Platypeza modesta, picta, aterrima, infumata, and fumipennis, males 

 have drab wings and black abdomen, females have light wings and 

 grey abdomen. 



Eristalis intricarius, male clothed with fulvous hair on the abdomen, 

 female with abdomen black with a white tip. 



Phasia subcoleoptrata, male with plain wings, female with dark 

 mottled wings. 



Musca maculata, male with fulvous red on the abdomen, female with 

 grey on the abdomen. 



Bibio hortulanus, anglicus, and ferruginatus, males are black, 

 females reddish yellow. 



Bibio marci, and leucopterus, males have light wings, females very 

 dark wings. 



Dilophus vulgaris, male has light wings, female very dark wings. I 

 have a hermaphrodite with one wing light, the other dark. 



Tipula lutescens, male has light wings, female yellowish wings. 



In the Hemiptera we find another colour difference ; for in the male 

 of Metatropis rufescens the knobs of the antennae and of the legs are 

 black, whilst in the female they are red. 



{To be continued.) 



