72 NEW YORK STATE MUSEUM 
marked dilatation of the lateral margins of the abdomen than even 
Oniscigaster wakefieldi. adits abdomen is more’ faa 
cnisciform: it is a veritable parachute. The expansion involves seg- 
ments 5 tog of the abdomen (inO. wakefieldi, only6tog), 
and begins and ends more abruptly than in the New Zealand 
species. Our insect distinguishes itself from Oniscigaster, how- 
ever, by lacking a median caudal seta, and by a symmetrical fork- 
ing of the median vein, that forking being very unsymmetrical in 
Oniscigaster. And since in these respects it agrees with the genus 
Siphlurus, which stands in the system next Oniscigaster, I was at 
first inclined, in spite of the parachute, which in Oniscigaster is 
certainly of no great systematic consequence, to refer it to Siph- 
lurus. By my key in Bulletin 86, N. Y. State Museum, page 22, 
it would be traced to Siphlurus, with the discrepancy that there is 
no backward prolongation of the sternite of the 9th abdominal seg- 
ment in the female. It differs from Siphlurus, also, in having the 
claws of the forefeet differentiated from those of the other feet, 
being obtuse and inflated and not at all clawlike in form: also, in 
having the radial sector in the hind wing twice dichotomously 
and symmetrically forked. I think therefore that this species repre- 
sents a genus distinct from both Siphlurus and Oniscigaster, 
although closely allied to both, and as such I describe it below. 
Probably the male, and the nymph if known, would add other 
differential characters. . 
Siphlonisca gen. nov. 
Caudal setae two, slightly longer than the body. Claws of the 
front tarsus inflated and obtuse; those on the other tarsi hooked 
and clawlike, and similar each to each. Hind tibia longer than its 
tarsus: last segment of tarsus longest, in all the feet. Median and 
cubital veins in the forewing symmetrically forked, and the radial 
sector in the hind wing equally twice forked: no humeral angula- 
tion of hind wing. Mesothorax with a prominent midventral 
spine. Abdomen with conspicuous lateral expansion of the middle 
segments. 
Type the following species. 
Siphlonisca aerodromia sp. nov. 
Length (2) 19 mm, setae 20 mm additional; expanse of wings 
37 mm. Abdomen 13 mm long and 2 mm wide, expanded to 4 mm 
wide on the 5th to 9th segments. 
