210 Annals Entomological Society of America [Vol. VI, 



the egg itself, for there seems to be no difference between eggs 

 just extruded and those carried for a couple of hours, half a 

 day, or longer. There is a constant regularity in the length of 

 time that elapses between copulation and extrusion of eggs, but 

 not in the length of time eggs are carried. Individuals in the 

 same cage eventually deposit their eggs in the same place, but 

 one may carry them two hours, and another nearly a day 

 under exactly the same conditions. 



I am in doubt as to the normal method of depositing eggs. 

 In the field, smaller species, carrying eggs, are often seen on 

 the stones in streams as if they were about to crawl down to the 

 water. And again they appear flying low along the stream and 

 dipping to the surface as if ovipositing. No such observations 

 have been made upon the larger species. The few adults of 

 Perla immarginata which have been seen dropping their eggs 

 in the pans seemed to do it more from accident than from 

 intention. They were crawling around the stones and had 

 floundered into the water. The instant they came in contact 

 with the water the eggs dropped to the bottom of the pan. 

 But many masses of eggs have been found in the pans too far 

 from the edge, or from the stones, for them to have been dropped 

 except from above, or by the individuals having actually crawled 

 into, or on the water. 



Concerning the place where the eggs are deposited there 

 is no doubt. When the globular mass touches the water the 

 eggs begin to separate. In the pans they finally settle down into 

 a patch one layer deep, (Fig. 6). Of course this is not the case 

 in the streams where the current scatters them broadcast. 

 They are not tossed about long, however, for as soon as they 

 come in contact with any object they become attached by the 

 glutinous cap which surrounds the micropylar apparatus. 

 These eggs are about half a millimeter long, dark brown in 

 color and oval-shaped. Except for a single circular ridge the 

 chorion is without ornamentation, (Fig. 7). 



In following the movement of the different adults from day 

 to day it was necessary to have some means of identifying 

 them as individuals. As has been previously stated, an abso- 

 lutely perfect adult is rare. Consequently it was a very simple 

 matter to recognize individuals on such characters as a broken 

 antenna 'or seta, a tarsus minus a segment or two, an imperfect 

 wing, and so on. In this way during the season thirty-two 



