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THE CANADIAN ENTOMOLOGIST 



latter being also straighter and more slender. The lateral setae 

 vary from 10 to 12, but are 11 in the great majority of cases. The 

 mental set* vary from 13 to 18 but are usually 14 or 15, with 8 

 to 10 in the stronger, outer series. 



Fig. 40. — Sympelriim pallipes, labium 

 of nymph from below. 



Fig. 41. — Sympelrutn costiferum, labium 

 of nymph from below. 



Sympetrum pallipes (Hagen). 



This species, which I reared in 1913 from nymphs taken from 

 small pools near Rock City, Vancouver Island, is extremely like 

 S. costiferum, though the adults are not closely related. It was 

 described in Can. Ent., 1914, vol. XLVI, p. 373,pl. XXV, Figs. 

 6-8. The lateral spines of segment 9 are usually, but by no means 

 always, shorter than in costiferum, and the- lateral lobes of the labium 

 tend to be somewhat more spinulose, the main spinules of the inner 

 margin being accompanied by two or three smaller ones forming 

 a graded series. In costiferum these accessory spinules are generally 

 fewer and shorter, some of the larger ones being single. (See 

 Can. Ent., loc. cit., pi. XXV, Figs. 8 and 12) but this charac- 

 ter is too variable to be of much value as a differential. The 

 labium is somewhat more slender and more narrowed at base, 

 being similar in form to that of ohtnisum. This character is ap- 

 parently a good one but is difficult to appreciate without examining 

 good series of both species. The lateral setae are usually 10, some- 

 times 11; the mental setae vary from 12 to 15. 



Judging from my limited experience in collecting the nymphs 

 of these two species, it would appear that they are ecologically 

 distinct, costiferum being an inhabitant of shallow, marshy bays 



