AQUATIC INSECTS IN NEW YORK STATE 283 
placed in a watch glass of water, these flaps will be seen to 
be separated, and there will be protruded between them four 
curved triangular, delicate, whitish, elongate gills, showing in 
their interior both tracheae and blood currents. These are 
doubtless respiratory appendages of the terminal portion of the 
walls of the rectum. A similar eversible condition of this part, 
with a much less perfect development 
of the gills themselves, has recently 
een described by Pantel in the 
Bulletin de la Société entomologique. de 
France, 1901, page 59-61, for a Tach- 
inid larva. The eversible portion of 
the rectum Pantel calls the anal 
vesicle, and to it he very properly 
attributes a respiratory function. 
These four gills in Epiphragma 
are comparable to the four anal 
processes of the larva next to be _ Fig. 18 anal gills of the larva of 
Epiphragma fascipennis 
described, and shown on plate 10, 
fig. 4, even to the constriction forming an apparent seg- 
ment near the tip. They are comparable and homologous 
doubtless with the anal processes of other Tipulidae. There, 
however, they are permanently on the outside of the body, 
being no longer retractile. The end of the rectum has become 
permanently everted in these more aquatic larvae. The larva 
of Epiphragma is therefore specially interesting as showing 
what has been the course of development of this part of the 
very curious caudal armature of the typical Tipulid larvae.t 
Larva [pl.9, fig.1]. Length 19mm; greatest diameter (base of 
thorax) 1.5mm. Cylindric, white, or faintly tinged with yellowish, 
with translucent sides and a brown head capsule. Head large, for 
the family, with pale antennae and labrum and stout blackish 
mandibles and labium. On the ventral side of each of the three 
thoracic segments is a pair of minute brownish points—vestiges 
————— —— — ——E) 
1Hlsewhere (American Naturalist, 86:185) I have pointed out, in a descrip- 
tion of the larva of Bibio fraternus, that the segmental tubercles 
have offered the material out of which have been formed the other fleshy 
tubercles which surround the caudal respiratory disk. 
