884 CHARLES PauL ALEXANDER 
Famity Ptychopteridae 
The family Ptychopteridae has generally been understood to include 
the tanyderid flies, as well as the three genera herein considered as con- 
stituting it. The resemblance between the Tanyderidae and the 
Ptychopteridae seems to be superficial only, however, and the differences 
are very considerable. 
The immature stages of the Ptychopteridae are very remarkable. 
The larva lives in an aquatic or a semi-aquatic habitat, and its caudal 
extremity is provided with an extensile elongated breathing tube which 
bears the spiracles at the end. The pupa has one of the two thoracic 
breathing horns enormously elongated, while the other is considerably 
atrophied. Both these elongated processes in the immature stages serve 
to provide the insect with air while the body is submerged beneath the 
mud and water. The larvae of Bittacomorpha are of a peculiar rust-red 
color; those of Bittacomorphella are almost black, with the short breathing 
horns yellow; those of Ptychoptera are more yellowish brown. 
The following key divides the family into its genera: 
1. Antennae 20-segmented; wings with cell M2 lacking; legs banded with black and ee 
(Subfamily Bittacomorphinae. Ee 
Antennae 16-segmented; wings with cell M, ‘present: legs not banded with black a 
white. (Subfamily Ptychopterinae.).................... Ptychoptera Meig. (p. 884) 
2. Apex of the wing not pubescent; metatarsi swollen....... Bittacomorpha Westw. (p. 884) 
Apex of the wing pubescent; metatarsi not swollen....... Bittacomorphella Alex. (p. 885) 
SUBFAMILY Ptychopterinae 
Genus Ptychoptera Meigen 
1803 Ptychoptera Meig. TIlliger’s Mag., vol. 2, p. 262. 
Ptychoptera rufocincta O. 8. 
1859 Ptychoptera rufocincta O.S. Proc. Acad. Nat. Sci. Phila., p. 252. 
Ptychoptera rufocincta is the only eastern species of Ptychoptera. It 
is deep black, with rusty-red bands on the abdominal segments; the wings 
(Plate XXX, 2) have brown crossbands, presenting an appearance super- 
ficially very like that of Limnophila macrocera. 
SUBFAMILY Bittacomorphinae 
Genus Bittacomorpha Westwood 
1835 Bittacomorpha Westw. London and Edinburgh Phil. Mag., vol. 6, p. 281. 
