AQUATIC INSECTS IN THE ADIRONDACKS 487 



margin of the prothorax. The dorsal shield of the prothorax farther 

 bounded on the posterior side by a transverse ridge, which curves forward 

 at its ends to terminate in a pair of prominent lateral processes ; there is 

 also an obtuse supra-coxa] process each side which extends forward close 

 beside the head halfway from the hind angles of the head to the eyes. 



Body depressed; legs smooth, wide apart, the three pairs successively 

 more remote from each other at base, the middle and hind femora each 

 with a superior ridge, the fore and middle tibiae each with a ridge, start- 

 ing at its base exteriorly (dorsally) and at once curving to extend down 

 its anterior face; tarsi three-jointed, the third joint about as long as the 

 two basal together, the claw short and stout, about as long as the basal 

 joint. 



Abdomen flat, suborbicular, granulate, with a row of oval smooth scars 

 midway between the median line and the lateral margin each side on 

 segments 4-8; wing cases reaching but to the middle of the fourth 

 abdommal segment (the nymph is apparently not grown); there is a row 

 of conspicuous dorsal hooks starting from between the wing cases and end- 

 ing on segment 9 ; strongly flattened laterally, not hooked at all, but erect, 

 and rounded on tips, highest on the sixth segment; ventral sutures wide 

 apart, slightly convergent posteriorly, disappearing on the ninth segment; 

 basal abdominal segments extremely contracted, segment i telescoped by 

 the metathorax, visible only in the middle of the ventral side; genitalia 

 { $) visible at the midventral apex of segment 2; lateral spines on 8 and 

 9, long and sharp, divergent on 8, parallel on 9 and as long as the 

 segment, greatly surpassing the appendages ; segment 9 excavate above 

 between the lateral spines, to inclose the annular loth segment and the 

 appendages, one half as long on the middorsal as on the midventral line ; 

 inferior appendages about as long as segment 9 is on the dorsal side, the 

 superior and the laterals successively shorter, the latter a little longer 

 than half the inferiors; segment 10 about half the dorsal length of the 

 ninth segment; inferior apical and lateral margins of the ninth segment 

 fringed with long hairs. 



A single nymph 1, sent me by Dr Calvert, from the collection of the 

 Academy of natural sciences of Philadelphia, bearing the label, 

 "H. C. Borden, Pa. Oct. 26, '95 ". 



The flat abdomen with erect blunt dorsal hooks and smooth lateral scars, 

 and the elongate third tarsal segment recall Ha genius, while the 

 broad mask- shaped labium, the vertical tubercles and the frontal ridge 

 recall Epicordulia. The transverse occipital ridge, the curving 

 carina on the fore and middle tibiae, and the extreme abbreviation of the 

 basal abdominal segments are characters which I do not recall having 

 observed in any other nymphs whatever. 



1 since the above was written I have received exuviae from Dr Calvert, taken at White lake In 

 the Catskills, and from E. B. Williamson, taken at Nashville Tenn., of this same species. The 

 length of the nymyh when grown is 21 mm, I now feel quite certain that these belong to Neu- 

 rocordulla. 



