27 



g. Median labial lobe entire ; female without genital 

 valves. Gomphidre. 



f. Eyes ])nt little separated, or meeting at a single point 

 dorsally ; median labial lobe bifid. 



Co t '(hi legasteridce. 

 c. Triangle of front wings with its long axis at right angles 

 to the length of the wing ; triangle of hind wings with 

 its long axis coincident with that of the wing ; ante- 

 cubitals of the first and second series mostly coinci- 

 dent ; second series of postcubitals incomplete at in- 

 ner end. LihelhdidcB 



Family PETALURIDiE. 



About all we know of the biology of this interesting fam- 

 ily is contained in two late papers by Williamson ('00a, '01) on 

 the recently discovered nymph and habits of the adult of our 

 single North American species, Tachopteryx thoreyi. This is 

 eastern and southern in its range, and has been found in an 

 adjoining state, Kentucky. While the adult has usually been 

 grouped with the Gomphidw, the nymph is nearest to the 

 ^schnidw, although it approaches nearer to both the Cordu- 

 legasteyid((' and Gompliida' than any other known form, possess- 

 ing a remarkal)ly synthetic combination of characters. The 

 adults were observed, according to Williamson, ovipositing in 

 boggy ground along a small hill-stream, where a single nymph 

 was found emerging. 



Family ^SCHNID^. 



The elongate nymphs of this family have a flat labium very 

 much like that of the Gonip/i/'dfc, consisting of a long mentum 

 bearing at its extremity a pair of curved appendages (the lat- 

 eral lobes) like the mandibles of a beetle, more or less toothed 

 on the inner edge and armed outwardly, toward the apex, with 

 a strong movable hook. The apical tooth of these appendages 

 is always present, not terminal and curved inward as in Gom- 

 phidce, but rather on the inner side of the squarely truncate or 



