AMKRICAN NEUROPTEKA. 117 



(Uily as chitinized spots. The teeth on tlie iuner edge of the hiteral 

 lol)e have increased in number, while those on either side of the 

 cleft in the ligula have disappeared, being represented only by a 

 band of chitin. The hairs along the border of the ligula, which, in 

 the early stages, were small, have inci'eased in size and covered the 

 entire border up to the cleft. The cleft is represented only by a 

 slight depression and by a line extending down upon the surface of 

 the mentum to about its original depth. 



KPIC'ORDIILIA, TETRAGOXEURIA and L,IBELL,UI.A. 



In contrast with Basiiescluia, in which the development tends 

 toward the disappearance of the teeth on both lateral lobe and 

 ligula, stand the reprepresentatives of the LibuUidre, Epicordulia 

 priiiceps, Tetragoneuria cyiio.nira, and Libellida pulchelld, in which 

 the tendency throughout the nymphal life is to increase in com- 

 plexity both lateral lobe and ligula. In the new hatched Epicor- 

 dulia (PI. II, Fig. 4) the ligula is comparatively simple. The cen- 

 ter is marked by a slight depression between two slight elevations, 

 while on either side is inserted a small spinule. Beneath these is a 

 line, probably the indication of a former suture, and beneath that, 

 six setigerous punctures. The second stage (PI. II, Fig. 5) shows a 

 number of teeth along the border of the ligula, while the two spinules 

 have increased considerably in size and four smaller ones have 

 developed, one above and one below the before mentioned suture, 

 on either side of the center of the ligula. In the third stage (PL II, 

 Fig. 6) the border of the ligula has become still more complicated, 

 the number of teeth has increased, and below and in the notches 

 between each pair of teeth is a spinule. These diminish in size 

 from the center to the edges of the ligula. The six setigerous 

 |)unctures have entirely disappeared. 



The new-hatched ligula of Tetragonuria (PI. II, Fig. 7) shows 

 almost exactly the same condition as the early stage oi Epicordulia. 

 The two spinules and the six irregularly placed setigerous punctures 

 are present, but the teeth between the setai are three in number and 

 are not uniform in size. Libellula pulchella shows the six setiger- 

 ous punctures placed some distance below the border of the mentum, 

 l)ut the spinules are absent and the border presents no distinctly 

 defined teeth, but instead, in the exact center, are four small irregu- 

 lar elevations. The lateral lobes of Libellula and of Epicordulia 

 are almost identical. 



TRANS. AM. ENT. SOC. XXX. MAY. 1904. 



