112 
DIPTERA. 
They form a small group, and several of the species are 
rare. Con ops rufipes and C. quadrifasciata are generally 
distributed and common ; the former has the second 
abdominal segment very attenuated, the posterior end 
thick; the abdomen of the other species is not very 
thin at the base. The flies of this family are prettily 
coloured, but not most gracefully formed. 
The Muscidce are, of all the various families of 
Diptera , the most remarkable, “ on account of their 
very numerous groups, species, and individuals, of their 
extensive variation of structure, and of their great im¬ 
portance in the economy of nature ; some species are 
insectivorous, many are parasitic in the larva state, the 
rest feed on living or decaying animal or vegetable 
matter” (Walker’s Diptera). The species are divided 
into two groups :— 
(1) . Calypterae, in which the alulae or winglets are 
distinct. 
(2) . Acalypterae, in which they are indistinct or 
absent. 
The former are distinguished by their comparatively 
large size, compact, dark, or metallic bodies, and fre¬ 
quently by the development of the fourth and fifth 
joints of the antennae or the basal joints of the arista. 
The insects of the latter group are comparatively small, 
with bodies less compact; their flight is more feeble, 
and the antennae are less developed. Mr. Staveley 
remarks that in the habits of both larva and fly in the 
several groups of genera in this one family, there is 
nearly as much variety as in all the other families of 
Brachycera together. Thus while among the flies are 
found flower-lovers feeding on honey, blood-suckers, 
