332 THE CANADIAN ENTOMOLOGIST 



ocelli and between eyes entirely brown or in some cases lighter 

 along median line and posterior margin. Antennae very hairy at 

 joints of basal halves, while apical halves are entirely bare and 

 become very slender. Margin and base of frontal piece hairy. 

 Clumps of hairs between eyes and at bases of antennae, in front of 

 lateral ocelli and posterior to eyes. Mandibular tusks ^ length 

 of antennae, upcurved, brown at tips, and with three longitudinal 

 TOWS of hairs. Prothorax has a broad longitudinal band of brown on 

 each side of middle line on dorsal surface, and is very hairy along 

 lateral margins. Mesothorax brown for the most part, dorsally. 

 Each abdominal segment has a large, almost triangular brown 

 area with two light areas within it; these light areas often reduced 

 to mere stripes. Ventrally on segments 6 to 8 there is a faint median 

 longitudinal dark streak, w^hile on ninth segment are two lateral 

 streaks. Setae of about equal length, and very hairy at joinings 

 for entire length. Gills and legs of usual Hexagenia type. 



Ephemera simidans Walker. 



The imagos of this species appeared from June 5th to July 

 27th, but were most abundant during the first two weeks in July. 

 The nymphs were not taken at Go-Home Bay, although diligent 

 search was made. The male imagos would appear shortly before 

 8 o'clock in the evening, and were often noticed in the morning, 

 also, as late as 10 o'clock. They would dance in swarms of a 

 couple of hundred individuals, usually at a height of from 10 to 35 

 feet. When a female appeared, several males would take after 

 her. The successful male, flying up beneath the female, would 

 seize her around the prothorax with his long fore legs, and bending 

 up his abdomen would grasp her abdomicn with his forceps, and 

 his penis could then be inserted in the oviducts. His setae usually 

 aided him in securing and maintaining his hold by being bent up 

 over the female's body. The couple would then go ofif on a gradual 

 downward slant toward the water, before reaching which the 

 male would disengage himself and fly back to the swarm, while 

 the female would fly out over the water and soon begin depositing 

 her eggs by skimming the surface of the water with her abdomen. 

 A peculiar thing was noticed, namely, that the male Ephemera 



