THE CANADIAN ENTOMOLOGIST 167 



rf Somatochlora semicircular is (Selys) . 



1 ha\'c a teneral iixiago of this species with the exuvia, taken 

 by Dr. A. G. Huntsman from a pond on Mt. Benson, near Nanai- 

 mo, B.C., on July 21, 1909. Dr. Huntsman states that both 

 nymphs and imagoes were common here. 



Nymphs (Figs. 26, 27) : Eyes rather small, but fairly promi- 

 nent; frontal ridge with numerous coarse hairs, its front margin 

 gently convexly curved; antennae with the basal segment slightly 

 shorter and stouter than the second, the third slender and nearly 

 as long as segs. 1 and 2, equal in length to 4.5 and to 6, 7 slightly 

 shorter. 



Head but little narrowed behind the eyes, the sides nearly 

 straight and about one-third as long as the posterior margin, which 

 is but little excavated; postero-lateral angles subrectangulate, 

 rather prominent, with numerous hairs. 



Labium extending back barely to the bases of the middle legs, 

 apical width of mentum about equal to its length, sides slightly 

 flaring distally; middle lobe moderately deflexed, obtusangulate, 

 the margin minutely crenulate and spinulose; lateral lobes concave 

 within, their inner margin with minute spinules of two or three 

 sizes, distal margin with 9 or 10 well-marked, obliquely-cut, apically 

 rounded teeth, each bearing a tuft of 3 or 4 spinules, of which the 

 innermost is the largest. Mental seta? 10 or 11; lateral seta? 6; 

 end-hook scarcely longer than the second antennal segment. 



Lateral margin of pronotum and supracoxal process hairy, the 

 former somewhat produced but rounded, the latter not very pro- 

 minent. 



Legs decidedly short, the hind femora being no longer than the 

 hind wing-cases, rather stout and fringed with moderately long 

 hairs. 



Abdomen elongate-ovate, about as wide as the thorax, but 

 little flattened, expanding but little from the broad base to seg. 5, 

 narrowing very slightly on 6 and 7, more rapidly on 8 and 9; lateral 

 margin fringed with hairs, which are long and dense, on 8 and 9; 

 much shorter on the other segments. Lateral spines present only 

 on seg. 9, somewhat less than one-third the length of the segment, 

 slender, subparallel, their sharp tips slightly incurved. Dorsal 



