240 



BUI.I.ETIN OF^ THE BUREAU OI^ FISHERIES. 



LIBELLULA PULCHELLA. 



A pair was taken mating on the north shore of pond 4D, and the female deposited 1,500 eggs. These 

 eggs were laid July 12; they began hatching July 22, and the hatching was completed by July 28. 



The Egg. — Curiously enough, the egg of this large species is smaller than that of the little Leucor- 

 rhinia. It is ellipsoidal in form, measuring 0.48 mm. in length and 0.29 mm. in width. The neck is 

 conical, the base nearly twice the height and without any visible segment, but the tip is divided; 

 there is no process at the posterior end of the egg. The yolk granules are small and indistinct. 



The Nymph. — This nymph is also just i mm. long; the head is one-third wider than long, one- 

 fourth the entire length; the abdomen is as wide as the head, with two rows of stout bristles on the 

 dorsal surface along either lateral margin; the latero-posterior appendages are very hairy. The antennae 

 are long and slender, black at the tips, with a single black band on the basal joint; the legs have black 

 and white bands, as shown in the figure; the eyes are straw yellow, with two larger black dots and 

 concentric rows of smaller ones; the head between the eyes and whole body is a pale yellow, deepening 

 into orange over the gizzard and rectum; there are whitened areas along the sides of the abdomen at 

 the posterior margins of segments 4 to 7, with darker areas anterior to them. The base of the antennae 

 is whitish, with a black distal band; first joint proximally gray, distally whitish; second joint nearly 

 all dark gray, with a narrow, white distal band; third joint dark gray, except the very tip, which is 



whitish. The whole body is transparent and pale white, a little yellowish on the head and at the 

 posterior end of the abdomen; the circulatory system is deeper white. 



The Mask. — Mentum three-quarters wider than long, distal margin two and a half times the length 

 of the proximal; foiu" setse on the inner surface, near the lateral margin, one proximal to them on the 

 margin itself; three mental setae on either side in nearly a straight line; two tiny spines at the center, 

 near the distal margin. Lateral lobes one-fourth longer than wide; two setae on the outen margin, near 

 the base; two setae on each blade; raptorial seta longer than the movable hook, the latter long and 

 narrow; distal margin with six teeth near the outer border, the first two the longest. 



HYBRID BETWEEN LIBELLULA PULCHELLA AND L. LUCTUOSA. 



A male L. pulchella and a female L. luctuosa were captured mating on the shore of pond 4D July 

 9, 1917. The female deposited about 100 eggs in a tumbler of water, and these subsequently hatched on 

 July 20. 



The Nymph. — This nymph is unlike those of either pulchella or luctuosa, especially in its markings. 

 The head is one-third wider than long, and the same width as the abdomen, grayish yellow; the eyes 

 are sulphur yellow, with small black retinal dots; the rest of the body is pale yellowish, but witliout 

 much color and quite transparent, except along the lateral margins of the abdomen, where each segment 

 is dark gray anteriorly and white posteriorly. The whole body is quite hairy, with a row of stout 



