DRAGONFLIES AND DAMSELFLIES IN PONDFISH CULTURE. 243 
PLATHEMIS LYDIA. 
The females of this species remain at some distance from the water, except at the time of ovipositing; 
one caught a quarter of a mile from the ponds deposited eggs freely on July 25, which began to hatch 
August 2, and were all hatched by August 9. 
The Egg.—tThese eggs are elongate elliptical and rather pointed at both ends, just twice as long as 
wide, the two diameters being respectively 0.60 mm.ando.30omm. ‘The neck isas wide at the base as it 
ishigh, with a distinct segmentation near the tip, the latter being undivided; there is no process on the 
posterior end of the egg. 
The Nymph.—The general color of the nymph is yellowish white, with light-brown markings. On 
the center of the dorsal surface of the head is a longitudinal, club-shaped, brown area and on either 
side a broken semicircle; there is a large, irregular, brown spot in the center of the posterior thorax and 
anterior abdomen, and another smaller spot over the posterior end of the respiratory system. The eyes 
are dark brown, with black, retinal spots; the tracheal system is yellowish brown. The head is a trifle 
wider than long and not narrowed behind the eyes; the thorax is two-thirds as wide as the head; the 
62 Ye 0.5 mm. ey 
Fics. 52 to s4.—Development of Plathemis lydia: 52, egg; 53, mask of newly hatched nymph; 54, newly hatched nymph. 
abdomen the same width as the head, sharply pointed posteriorly, with strongly convex, lateral margins 
and no color markings except the two spots already noted. The base and basal joint of the antenne are 
whitish; proximal end of second joint and the whole of the third joint light gray, distal part of second 
joint white. The legs are light gray and white; the tips of the posterior processes of the abdomen are 
dark brown; the terga of the thoracic segments are light gray. 
The Mask.—Mentum twice as wide as long, with convex sides; distal margin two and a half times 
the proximal; one lateral seta near the base on each side and two marginal sete; three mental sete on 
either side of the center in a curve concave to the midline; two small spines at the center of the 
distal margin. Lateral lobes one-half longer than wide; two sete on the outer border, none on the 
blade; raptorial seta just reaching the tip of the movable hook, the latter short and stout; distal 
margin with seven teeth reaching nearly the entire width, the third tooth the longest. 
EPICORDULIA PRINCEPS. 
The eggs of this species are laid in long, jelly-like strings, similar to those of Tetragoneuria. Some 
of these strings were obtained from the leaves of Potamogeton illinoiensis in pond 3D on August 9, 1917; 
but, of course, there was no way to tell when they were laid; they began to hatch within a day or two. 
The Egg.—This egg is the largest of any here described, being 0.72 mm. long and 0.40 mm. wide. 
The neck is a minute process of the same height and width, without segmentation, and there is no process 
on the posterior end of the egg. 
