286 NEW ^-ORK 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 (flg.l9). Seyenth abdominal segment inflated. 

 Ko 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 scA^enth seg- 

 ment. Spiracles black, seated on a narrow and imperfect respi- 

 ratory disk [pi. 10, fig.o], 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. o r n a t a and C. t h o r a c i c a), are 

 common at Ithaca, and this larva may belong to one of these. 



Larva. Length IGmni; caudal filaments (arising from the ven- 

 tral border of the respiratory disk) 3mm additional; diameter 

 2mm. 



Color dark greenish; skin subrugose, somewhat shining. 

 Bodv nearly cvlindric, 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 



