GEORGIAN BAY EPHEMERID^ 133 



SESSIONAL PAPER No. 39b 



in some forms. Eyes simple; large, especially in male. Antennae short, 1 to 1*5 ram. 

 Setae 2§ to 3 times length of body; segments of basal half alternately darkened; 

 minutely pubescent. Penis lobes extend backwards and outwards, almost L- 

 shaped. In some forms the lateral extension lacking and hence rather oblong 

 in shape. Stimuli adjacent between the lobes. 



The species which I have taken fall into two distinct groups: — 

 In the first group, consisting of H. tripunctata, H. luridipennis, H. fiavescens, 

 H. rubromaculata, H. fusca, H . Lutea, the nymphs are characterized by having 

 the lamellae of the gills oblong, claws usually pectinated, the distal segment of 

 maxUlary palpus thickest about its middle and with a small tuft of hair near its 

 end. The body is much flattened and the colour more or less brown. The male 

 imagos have the penis-lobes L-shaped and the 2nd and 3rd tarsal segments of 

 fore leg are equal, while the fourth is about 4/5 the length of the 2nd. 



In group 2, consisting of H. canadensis, H. frontalis and a third undetermined 

 species represented by the nymph only, the nymphs have the lamellae of the 

 gills oval and produced distally into a sharp point; claws are not pectinated, the 

 distal segment of maxUlary palpus thickest toward distal end and the tuft of hair is 

 larger than in group 1; usually there are more teeth along anterior margin of 

 lacinia. The body is less flattened and more reddish or yellowish. The male 

 imagos have the penis lobes oblong, not L-shaped and the 2nd and 3rd tarsal 

 segments not quite equal, while the 4th segment is about J the length of the second. 



Key to Male Imagos 



A. No black spots or bands on face below antennae. Group 1. 

 B. Very pale species. 



c. Notum ferruginous, stigmal dots distinct H. fiavescens. 



c.c. Notum lighter; no stigmal dots H. lutea. 



B.B. Dark species. 



D. Large, entirely brown species. 



E. Thorax with a broad dark median stripe or two narrow stripes 

 close together H. verticis. 



E.E. Thorax without dark median stripe H. fusca. 



D.D. Not entirely brown 



F. Two very small dots on median carina between antennae 



H. luridipennis. 



F.F No dots on median carina. Thorax and top of abdomen dark. 

 G. Reddish area in pterostigmatic space of wing. 



H. rubromaculata. 



GG. Without reddish area in wing H. luridipennis. 



AA. Two black spots or bands on face below antennae, Group II. 



H, A black band on face below antennae, a dark dash in wing. 



Abdomen dark H. canadensis. 



HH. A black spot on face below antennae, no dash in wing, 



abdomen lighter H. frontalis. 



396—91 u 



