51 



When the nymphs are ready to leave the water to trans- 

 form they cannot ascend very small stems, such as those of 

 reeds, owing to the wide divergence and separation of the legs; 

 but they can readily climb up on a broad surface like the 

 piers and timbers of a bridge or the side of a floating barge, or 

 on large rocks or tangled growths. They do not go far above 

 the water, not more than a few feet at most, and here they may 

 be seen transforming at any hour of the day or night, but 

 most commonly about daybreak, leaving behind them their 

 mud-incrusted shells, which are often seen in great numbers in 

 the situations already mentioned. A study of the different 

 sizes of larvae indicates that the nymphs require two or three 

 years to attain maturity. 



The imago gomphid is in most species a medium-sized 

 clear-winged dragon-fly, the thorax rather prettily striped with 

 green or yellow, the abdomen rather slender in comparison 

 with the thorax but often dilated towards the tip, the eyes not 

 touching as in the ^Esrhnidce and remaining Anisoptera, but 

 widely separated as in the Agrionidce and Petaluridce. In wing 

 venation they approach the LihelluUdce, the triangles being well 

 differentiated, with few or no cross-veins, but the antecubital 

 cross-veins are mostly non-coincident, as in the other Ani- 

 soptera. The anal loop is small, inclosing from one to a few 

 cells. As with the LihelluUdce, the ovipositor is not developed, 

 and the more or less oval eggs are transferred free to the water 

 by successive taps at its surface with the tip of the abdomen 

 during flight, the females ovipositing alone.* The number of 

 eggs deposited is very large. Copulation takes place while at 

 rest on shore. The females frequent the trees or pathways back 

 of the shore, while the males rest nearer the water. The latter 

 may be quickly recognized by their curious terminal append- 

 ages resembling four fingers about to grasp something, while 

 those of the female are short, simple, and inconspicuous. The 

 period of flight usually occurs rather early in the season, vary- 



♦The eggs in a Nymphcea leaf figured by Lampert, '99, as eggs of Gomphus 

 have been demonstrated by our breeding work at Havana to be those of Agrionida- 



