41i THE CANADIAN ENTOMOLOGIST 



THE NYMPHS OF THE NORTH AMERICAN SPECIES OF 



LEUCORRHINIA. 



BY E. M. WALKER, TORONTO. 



Through ihc kindness of Mr. F. C. Whitehouse, of Red Deer, 

 Alta., who has been actively collecting and studying the Odonate 

 fauna of this locality during the past two years, I have recently 

 obtained nymph exuvise of Lencorrhinia borealis Hagen and L. 

 proxima Calvert, the only two North American species of this 

 genus, whose nymphs have not yet been described. Recently- 

 emerged imagines of both species, as well as of L. hndsonica were 

 found by Mr. Whitehouse, accompanied by their exuvia?, so that 

 in addition to the finding of the two new nymphs he has been able 

 to furnish the information necessary to prove that the nymph 

 described b\- me as that of hndsonica* was correctly referred to this 

 species. 



The nymphs of Leucorrhinia may be characterized as follows: — 

 Head somewhat less llum twice as broad as long, eyes most promi- 

 nent behind the middle, lateral margins very oblique, curving into 

 the posterior margin without any indication of an angle. Mentum 

 of labium about as broad as long, mental seta? usually 13-15, inner 

 margins of lateral lobes with very low crenulations, the marginal 

 spinules in groups of two or three, of which one is much the longest, 

 sometimes single; moveable hood slender, scarcely half as long as 

 the free margin of the lateral lobe; lateral seta? 10 or 11. Abdomen 

 ovate in outline, broader than the head, broadest at segment 6, 

 tapering almost equally cephalad and caudad; lateral spines 

 present only on segments 8 and 9, those on 9 not extending beyond 

 apices of abdominal appendages; dorsal hooks present or absent, 

 but never oti segment 9; superior appendage triangular, acuminate, 

 distinctly longer than broad, but little shorter than the inferior 

 appendages; lateral appendages about half as long as the inferiors. 



I have been able to find no good characters for the separation 



of nymphs of Leucorrhinia and Sympetrum. Generally speaking, 



the ^perior abdominal appendage is somewhat more elongate and 



acuminate in Leucorrhinia, being considerably longer than the 



basal breadth a nd not much shorter than the inferior appendages. 



* Can. Ent., 1914, vol. XLVI, p. 375, pi. XXV, figs. 9-12 

 December, 191G 



