ON INDIAN PARASITIC FLIES. 371 
pair of claws and a pair of pads between them. The claws may be 
extremely slender but in parasitic flies they tend to become strong 
and serrated. 
The antenne of flies show much variety and have, since the days 
of Latreille (1802), been regarded as furnishing fundamental charac- 
ters for classification. They are of two types. The primitive type 
of antenna is Nematocerous (which means long-horned) and consists of a 
number of nearly similar jomts. The Brachycerous (or short-horned) 
type appears to consist of only three joints dissimilar from one another, 
On closer examination the last is seen to be more or less distinctly 
ringed and to be made up of several joints. The complex antenna of 
the most highly specialised flies has, in fact, been evolved from the 
simple Nematocerous antenna by a concentration of the basal joints 
and an elongation of the distal. In the parasitic flies this latter type 
of antenna is very much reduced. Sometimes only a single joint with 
a few bristles is recognisable ; and this is sunk in a deep pit on the 
head from which it can be protruded by the contraction of the muscles 
at the base. 
This is no place to enter into the controversies that have raged 
around the homologies of the dipterous mouth parts. The fly’s 
mouth is adapted for sucking and, sometimes, for piercing and sucking. 
The mouth parts project beyond the head and form a more or less 
cylindrical proboscis. In some of the parasitic Hippoboscid flies the 
proboscis can be almost completely withdrawn within the head. 
Whilst in the Cistrid flies, in which the larva is parasitic and the per- 
fect insect does not feed, the mouth parts are rudimentary or absent. 
In all typical flies the proboscis is formed of the labiuwm, or lower lip 
which encloses and sheaths the other parts, which may be 
variously modified and some of which may be absent. 
The reader, who knows anything of entomology, need only be 
reminded that the order Diptera is divided into two large groups or 
sub-orders the Orthorrhapha and Cyclorrhapha. The main difference 
between these two groups turns upon the manner in which the insect 
emerges from the pupal envelope. In the Orthorrhapha the pupa 
is mummy-like and shows, in outline, the parts of the future imago 
which escapes by splitting the skin down the back. In the Cyclorr- 
hapha the pupa is like a small barrel, showing only rings outside and 
nothing of the future imago within. The fly emerges by pushing off a 
circular cap. The group of flies known as Pupipara, because the larva 
is retaied within the mother’s body and there nourished until it is 
ready to pupate, are Cyclorrhaphous flies much modified by parasi- 
tism. 
The connection that, apparently, exists between development of 
squame or tegule and parasitic habits deserves attention. It seems 
to be chiefly those groups containing a large proportion of entopara- 
sitic species that are provided with tegulle ; and it is possible that 
