DIPTERA. — PUPIPARA. 581 
ficiently strong to warrant the establishment of the insects into a 
distinct order, changed to Omaloptera, which MacLeay, with more 
precision, altered to Homaloptera, regarding it however merely as an 
osculant group. In the more recent works of Latreille, they are 
still recorded as a primary section of the order Diptera, under the 
name of PupipaRra (suggested by Réaumur’s name of Nymphipares). 
Although Dr. Leach has been followed by several English Ento- 
mologists, it will be seen that Messrs. Kirby and Spence introduced 
the Pupipara amongst the Diptera; and, indeed, when we consider 
the modifications to which the true Diptera are subject in every ma- 
terial character — mouth antenne, transformations — we are fully 
warranted in retaining these insects in the order Diptera, as well as 
in considering it to be possible that other Diptera will be found in- 
termediate between them and the true Diptera. 
These insects form two families, Hippoboscide and Nycteribiide. 
The Hippososcip# (or the Coriacea Latr.) have the head always an- 
terior and distinct ; the legs are short and robust, with the 5th joint of 
the tarsi the longest. The head of these insects is generally circular 
(jig. 133.3. head of H. equina above, 4. beneath), and is closely united 
to the thorax, being inserted without any distinct neck into the frontal 
cavity of the latter; the eyes are often very large, occupying the entire 
sides of the head ; the anterior part of the head, or clypeus, is distinct, 
and separated by a curved impression from the latter. This clypeus 
is of a reversed heartshaped form, having the antennz immersed in 
the anterior angles; these organs, when extracted, are either of a 
rounded shape, having several bristles arising from their external part 
(fig. 133. 5. ant. of H. equina), or plate-like and bristly. Many er- 
roneous views have been entertained respecting the structure of the 
mouth ; and the opinions of authors, upon the affinities of these insects, 
have thence been very unsettled. It is only very recently that the true 
formation has been shown by Curtis, Latreille, Newport, Dugés, and 
in the posthumous work of Lyonnett, whose views I have confirmed by 
dissection, whereby I am enabled to add a few observations to what 
has been previously recorded. The anterior portion of the under sur- 
face of the head in Hippobosca is covered with a membranous plate, 
which, at its apex, is furnished with a small central orifice, and at the 
sides with a pair of coriaceous plates, narrow, elongated, and bristly, 
extending beyond the front of the head, and forming, when in inaction, 
a kind of rostrum, as in fig. 133. 11. 
