7- NEW YORK STATE MUSEUM 



marked dilatation of the lateral margins of the abdomen than even 

 Uniscigaster wakefieldi. Its abdomen is more than 

 onisciform: it is st veritable parachute. The expansion involves seg- 

 ments 5 to 9 of the abdomen (in O . wakefieldi, only 6 to 9), 

 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 (5) 19 mm, setae 20 mm additional; expanse of wings 

 ;^j mm. Abdomen 13 mm long and 2 mm wide, expanded to 4 mm 

 wide on the 5th to 9th segments. 



