286 NEW YORK STATE MUSEUM 
Larva. -Length 42mm; greatest diameter of thorax 5mm; of — 
abdomen 7mm. Body cylindric, smooth, white translucent, with 
unusually abrupt narrowing at the anterior end to the wholly 
retractile head (fig.19). Seventh abdominal segment inflated. 
No surface hairs or spines; but on the ventral side of the three 
thoracic segments are three pairs of spine-tipped structures 
which I take to be the rudiments of the thoracic legs. 
There are stout, brownish prolegs on abdominal segments ~ 
4-7, paired and separate on 4, becoming completely fused on - 
succeeding segments into a transverse ridge, each proleg capped 
with a mere obtuse hillock of chitin, bearing no hooks or spines. 
Abdomen strongly tapering beyond the inflated seventh seg- 
ment. Spiracles black, seated on a narrow and imperfect respi- 
ratory disk [pl.10, fig.5], whose dorsal margin is indicated only 
by a slight ridge, and from whose ventral side arise two long 
processes, approximated at base, tapering, slightly granulate 
before the tip, and with about six to eight minute, fragile, un- 
equal hairs on the obtuse apex. Anal aperture surrounded by 
four equal, taper, pointed, white appendages, each showing a 
tendency to the formation of a telescopic joint at two thirds its 
length. | 
An unknown Leptid larva from rapid streams 
On plate 10, figure 1 we show a curious larva that seems 
clearly to belong to the family Leptidae, but that differs con- 
siderably in structure from the Leptid larvae hitherto made 
known. I first collected small specimens from the rapids in 
Six Mile creek at Ithaca in December 1896. During the sum- 
mer of 1901 larger larvae were frequently found in Fall creek. 
They live in the crevices of the stones in rushing waters, asso- 
ciated with stone fly and caddis fly larvae. But few specimens 
were obtained, and no attempt was made to rear them. Two 
species of Chrysopila, (C. ornata and C. thoracica), are 
common at Ithaca, and this larva may belong to one of these. 
Larva. Length 16mm; caudal filaments (arising from the ven- 
tral border of the respiratory disk) 8mm additional; diameter 
2mm. : 
Color dark greenish; skin subrugose, somewhat shining. 
Body nearly cylindric, slightly thickest on the sixth abdominal 
segment, with strongly tapering metathorax and mesothorax, 
slender and attenuate prothorax and strongly retractile head. 
The median ridge of the head is very prominent in front, shaped 
like an inverted sled runner. Antennae prominent, slender, 
two jointed. Mandibles ending in strong, ventrally directed 
