AQUATIC INSECTS IN THE ADIRONDACKS 5II 



Nymph, (fig. 29) Fully grown, measures in total length of body 

 10 mm; abdomen 5.5 mm; hind femur 3.5 mm; width of head 3.5 

 mm, of abdomen 4 mm. 



Color almost uniform tawny yellowish brown, paler below and on the 

 sutures, more or less completely obscured by adherent vegetable debris. 

 Body moderately hairy on lateral margins, specially hairy toward the 

 end of the abdomen. 



Head compact, one third wider than long, scurfy hairy above excepting 

 a pair of bare spots near the hind margin, with prominent hemispheric, 

 eyes covering the anterolateral angles, narrower behind the eyes with 

 parallel sides, rounded hind angles, and almost straight hind margin. 



Antennae shorter than the head, is long, seven-jointed, with scattering 

 hairs along the distal joints. Labium extending posteriorly between the 

 bases of the fore legs ; median lobe broadly triangular, half as long as 

 wide, rounded on tip, with two spinules close together just before the 

 tip, and several others each side along the front border farther apart; 

 raptorial setae on the mentum, 10 each side, the fourth or fifth (counting 

 from the side) longest, the three innermost ones quite small; lateral 

 labial lobes ample, with six raptorial setae, and a spinule at the base ; 

 hook straightish to the slender slightly curved tip, hardly longer than the 

 setae, but much stouter ; teeth almost obsolete, bispinulose. 



Prothorax with prominent spiracles; legs hairy, specially the tibiae 

 externally; tarsal claws not strongly incurved; second tarsal joint one 

 half longer than the first, and the third one half longer than the second ; 

 wings reaching well on the sixth abdominal segment. 



Abdomen somewhat depressed, oblong, widest on the sixth segment, 

 the ninth segment as wide as the second ; narrowed with extraordinary 

 abruptness on the loth segment, which is almost included within the 

 apex of the ninth. No dorsal hooks at all; in their places are tufts of a 

 few long hairs, and whitish spots in the ante-apical membrane of the 

 segments. Lateral spines on segments 8 afid 9, hookhke, starting 

 outward at base, and incurved at tip, on eight one half the length of the 

 segment, on nine, a little longer than on eight. Hairs on the apical 

 carinae well developed, specially so on segment nine, which they com- 

 pletely incircle, constituting a long fringe which completely overhangs 

 the loth segment and the appendages. Appendages about as long as 

 the ninth segment is on its slightly shorter dorsal side ; lateral appendages 

 a third shorter. 



Since the discovery and description of the nymyh of Tachopteryx 

 thoreyi Selys by Messrs Graf and Williamson, last year, this species 

 has remained the most important discovery to be made. It is our only 

 representative of that singular group of Libelluline genera which Karsch 

 called the Nannophyae.^ Mr Weith's zeal and industry have brought 

 this nymph to light, and there now remains of all the genera of Odonata 

 of the northern United States and Canada but two in which no nymph 

 are known, and they are Goraphaeschna and Micrathyria. 



PERITHEMIS 



There is a single species occurring within the state. 



^ Ent. Kachr. 15 : 245-63. 



