166 THE CANADIAN ENTOMOLOGIST 



two pale rings — a median and an anteapical. Abdomen yellowish 

 brown, more or less distinctly blotched with dark brown, especi- 

 ally on the dorsal hooks, the lateral margins and spines and the 

 dorso-lateral scars. 



Measurements. — Length of body 22-24.5; mentum of labium 

 4; hind wing 6-7; hind femur 5.5-6; width of abdomen 9-10; 

 width of head 6.5. 



The nymph of this species shows the following diffcrences- 

 from that of A^. obsoleta (Figs. 18-19), two exuvite of which I have 

 from Lake Hopatkong, Pa., received from Professor P. P. Calvert. 



Somewhat larger, more elongate, and less depressed; eyes 

 somewhat less prominent, mentum of labium a little longer and 

 more narrowed at base; middle and hind legs somewhat less widely 

 separated at their bases; abdomen narrower, the sides less strongly 

 curved on' the middle segments; lateral spines on seg. 9 much 

 shorter than those of obsoleta, in which they are fully as long as. 

 the segment and extend far beyond the tips of the appendages; 

 dorsal hooks also less developed than in obsoleta, in which they 

 form quite prominent tubercles on segs. 7-9. 



Tetragoneuria spinigera Selys. 



We have reared only two females of this species, these emerg- 

 ing on June 2, 1912, at a time when the period for transformation 

 was about over. We also found a teneral male with its cxuvia on 

 June 1 and a large number of similar exuvia, which must belong to 

 T. spinigera as T. cynosura simulans, the only other species resi- 

 dent in the Go Home Bay district, does not appear until a little 

 later in the season. 



A careful comparison was made between the exuvia? of these 

 two species, but no differences could be detected between them, 

 except that in spinigera the lateral abdominal appendages average 

 slightly longer than those of cynosura. This difference, howe\'er, 

 does not appear to be constant. Prof. Needham, who referred 

 certain nymphs to this species by supposition, employed as dif- 

 ferential characters the length and amount of divergence of the 

 lateral spines of segment 9. The two species discussed here are 

 quite alike in respect to these features, which vary considerably 

 among individuals of the same species. 



