DRAGONFUES AND DAMSELFUES IN PONDFISH CULTURE. 



241 



bristles along the dorsal surface of the abdomen, between the respiratory system and the lateral margin 

 on either side. The antennae are relatively large; base white with a pale grayish distal band; first 

 joint white through the center, pale grayish at either end; second joint with proximal three-fifths dark 

 and distal two-fifths white; third 

 joint dark, tipped with white. 

 These nymphs did not ascend 

 to the surface of the water, like 

 those of luctuosa, but stayed 

 down near the bottom of the 

 tumbler. 



The Mask. — Mentum twice 

 as wide as long; the distal bor- 

 der two and a half times the 

 proximal; the lateral margins 

 curved; three setae on either 

 side, near the lateral margin; 

 three mental setae in a straight 

 line; a slight lobed promi- 

 nence behind the center of the 

 distal margin, without spines. 



Lateral lobes one-third longer than wide; two setae on the outer border near the base; two on each 

 blade; raptorial seta considerably longer than the movable hook, the latter short and slender; distal 

 margin with four teeth near the outer edge, the first two the longest. 



ERYTHEMIS SIMPLICICOLLIS. 



The first females were seen laying in pond 4D on July 12, 1917. Eggs laid July 13 hatched July 23. 



The Egg, — The egg of this species is an elongated ellipse, with rather pointed ends, and is a little 

 more than twice as long as wide, the respective diameters being 0.60 mm. and 0.27 mm. The neck 

 has a base narrower than its height, divided at the tip; there is a small process on the posterior end 

 of the egg; the yolk granules are minute. 



The Nymph. — This nymph has the most pigment of any of those examined, and is banded brown 

 and yellowish white; the eyes are light orange yellow with comparatively large black spots; the sides 

 of the head are brown shading into light yellow on the median line; each thorax segment is brown 



Figs. 44 and 45.— Hybrid from male Libellula pulchella and female Libellula luctuosa: 

 44, mask of newly hatched hybrid nymph; 45, newly hatched hybrid nymph. 



47 0. 5 mm. 



Figs. 46 to 48. — Development of Erythemis siynplicicollis: 46, egg; 47, mask of newly hatched nymph; 48, newly hatched nymph. 



bordered with dark yellow along the lateral margins and light yellow in the center, thus leaving a clear 

 yellow longitudinal streak through the center of the body; the ninth and tenth segments are yellow; 

 the legs are dark proximally, with a white band across the distal ends of the coxae, femora, and tibiae. 

 The central yellow line of the head passes over the forehead and down between the antennae onto the 

 labrum. On the back of the head it is widened considerably and usually runs out into two rounded 

 points on either side, with two small, brown spots, one on either side of the midline, at the level of the 

 posterior points. Through the thorax it is narrow, then widens again on the first three or four abdomen 



