312 
CLASS VIII. 
a thread through the eye of a needle, Westwoop). These threads 
are very long in Melophila and Ornithomyia, shorter in Hippobosca. 
Two oblong hairy plates project like a beak and cover the base of the 
threads when they are exserted. Are these parts to be regarded as 
maxille, or as palpi maxillares? The mechanism of the sucker is 
much more conformable to that of certain Acarina than to the 
proboscis of the rest of the Diptera. 
These flies lay no eggs, but are viviparous. That which seems to 
be an egg laid by these insects, and which is sometimes as big as the 
abdomen of the mother, ought rather to be regarded as a pupa ; 
from it the perfect insect (¢mago) comes to view after an interval of 
time, dependent upon the temperature to which the pupa is ex- 
posed. . 
The intestinal canal of these insects is very long, and surpasses 
the length of the body eight or nine times. This length is caused 
principally by the stomach, or that part of the intestinal canal 
which precedes the insertion of the vasa urinaria, and which presents 
many tortuosities. The testes are two long and very tortuous 
canals; the ovaries, two oval sacs; near the oviducts are two 
secretory glands, consisting of very numerous branches, together 
with two more simple receptacula seminis, of which the form varies 
in different species. The lowest part of the two ovaries opens into 
a wide sac (uterus, matrice Lion Durour), in which the embryo 
resides until it comes forth as a pupa. The nervous system has, 
besides the cerebral ganglion, only a single round ganglion in the 
thorax, from the posterior margin of which the nerves of the 
abdomen arise. 
Comp. on the anatomy of this family, Leon Durour, Rech. anatomiques 
sur V Hippobosque, Ann. des Sc. nat. V1. 1825, pp. 299—322. Pl. 13: also 
his Etudes anatomiques et physiologiques sur les Pupipares, Ann. des Se. nat. 
troisitme Sér. Zool. Tom. 11. 1845, pp. 49—95. Pl. 2, 3. 
Phalanx I. Nyctertbiide. Head small, placed at the upper 
part of the thorax like an obconical tubercle. Thorax semi- 
orbicular. Wings and: poisers none. Feet long, with first joint 
of tarsus very long, and last supplied with two claws incurved, den- 
tigerous at the base, and with two oval appendages. 
Nycteribia Lar. 
Sp. Nycteribia vespertilionis, Acarus vespertilionis L., Phthiridium vesperti- 
lionts Herm., Mém. apterol. Pl. v. fig. 1; Nycteribia Latreillii WESTW., 
“sal a 
= tea 
op Rae 
