DIPTERA. 319 
cle, composed of two closely approximated threads or sete, 
and covered by two coriaceous, narrow, elongated, and pilose 
lamine which form its sheath. Whether these lamine or 
valvule represent (as I presume) the palpi of other Diptera, 
or whether they be parts of a true sheath, as is the opinion 
of M. Dufour in speaking of a species of Ornithomyia—Ann. 
des Sc. Nat., X, 243, XI, 1—where he has discovered two 
little bodies which he considers as palpi(1), it is not less a 
fact that the proboscis of these Insects evidently differs from 
that of the preceding Diptera, and that the sheath, in this 
case, would be more analogous to the proboscis of the Flea, 
from which however it is removed by the absence of articula- 
tions. 
The body is short, tolerably broad, flattened and defended 
by a solid skin almost of the consistence of leather. The head 
is more intimately united to the thorax than in the preceding 
families. ‘The antennz, always situated at the lateral and 
anterior extremities of the head, sometimes form a tubercle 
bearing three sete, and sometimes little hairy lamine. The 
eyes vary as to size; in some species they are very small. 
M. Leon Dufour, in his description of the Ornithomyie 
bilobee, has observed that although this genus has had ocelli 
attributed to it, he has not been able to discover them. A 
fresh examination of such species as I could procure has in 
fact convinced me that we were mistaken(2), and it may be 
considered as a general rule that the Pupipara are destitute 
of those organs. The thorax presents four stigmata, two an- 
terior and two posterior. ‘The learned entomologist just re- 
ferred to, in the Hippobosca equina of which he has de- 
scribed the Anatomy—Ann. des Se. Nat., VI, 299, et seq.— 
could only find the two first, those which are situated on the 
lateral and anterior extremities of the mesothorax ; but I have 
(1) In the Melophagi, the base of the laminz of the sucker is covered by two 
little coriaceous, triangular and united pieces, forming a sort of labrum. They 
seem to form a miniature representation of the two pieces that cover the base of 
the proboscis of the Flea. 
(2) Dr Leach, however, admits that they exist in certain species. 
