1913] Biology of May-flies. 373 



eggs in the water. He counted the eggs which he found pro- 

 truding from the abdomens and determined the average num- 

 ber to be 750 to 800 for each female. He disagreed with 

 Swammerdam regarding the fertihzation of the eggs, and stated 

 that the males and females probably did mate, and that the 

 forceps of the male were evidently for the purpose of seizing 

 the female. 



DeGeer. 1748. In 1748 DeGeer saw the mating* ac- 

 tually take place. Two years later he again saw the mating 

 flight and the mating, and this time was able to give more 

 facts concerning it. The swarm consisted mostly of males. 

 In mating the male was beneath the female with his abdomen 

 recurved upward so that its tip rested against the two openings 

 of the oviducts, between the eighth and ninth segments. Cop- 

 ulation lasted but an instant, and De Geer was not able to 

 observe the process in detail. He described several different 

 varieties of May-flies, distinguishing them by descriptive 

 color names. The double eyes of a diurnal May-fly (possibly 

 a Leptophlebia) were mentioned, the larger eyes being named 

 the turbinate eyes.f 



G^offroy. 1764. Geoffroy, 1764, saw great swarms of May- 

 flies near Paris and noted that there they were called "manne 

 de poissons," because great numbers fell down into the streams 

 to the fishes. He accurately figured and described as a Crus- 

 tacean,'! "the May-fly, later determined by Vayssiere as Pro- 

 sopistoma, which he found in the riffles of a stream near Paris. 



Newman, 1836. In discussing the transformations of in- 

 sects, Newman, 1836, wrote of May-flies as follows: "Here 

 then we have the strange fact of an insect's flying before it 

 reaches the imago; that is, flying in the penultimate state. 

 It thus appears that although until the final ecdysis, no insect 

 arrives at perfection; yet before that period, even in the state 

 immediately preceding, it may feed, run and even fly; or it 

 may swim, crawl, barely move, or be without motion." 



Bowerbank, 1833. Bowerbank studied the circulation of 

 the blood in young nymphs of Ephemera marginata. He 

 carefully examined the dorsal vessel with its valves and de- 

 scribed the circulation of the blood. He was the first to see 



*DeGeer, 1748, T. II, p. 644. 

 fDeGeer, 1748, T. II, p. 651. 

 JGeoffroy, Tom. II, p. 658. "Le Binnocle a queue en plumet." 



