416 THE CANADIAN ENTOMOLOGIST 



and lagoons, while pallipes, like its near relative ohtrusum, prefers 

 small, semi-permanent ponds and puddles. 



Sympetrum obtrusum (Hagen). 



The nymph of ohtrusum, of Avhich I have bred several speci- 

 mens of both sexes, is very like that of pallipes but is somewhat 

 snialler and the shorter dorsal hooks and lateral spines seem to 

 be good characters, though tlie opposite extremes in the two 

 species approach one another closely. The lateral setae are nor- 

 mally 10, the basal one being, however, very small and sometimes 

 absent. The mental setae are usually 12 or 13, occasionally 14. 

 Sympetrum rubicundulum (Say). 



As already mentioned, the nymph of this species has been 

 described by Needham^ and the characters as given in his descrip- 

 tion apply equally well to 5. ohtrusum, from which he was unable 

 to distinguish it. Specimens of nymphs and exuviae from a puddle 

 at Prince Albert, Sask., where I found S. ruhicundiilum decisum 

 (Hag.) emerging, differ from ohtrusum in the great reduction or 

 even absence of the dorsal hooks, and in the smaller lateral spines. 

 These characters appear to be good but I have only seven speci- 

 mens, and the variation among them is considerable. 



During early July, 1917, I found a number of Sympetrum 

 nymphs in several small puddles at De Grassi Point, Ont., and be- 

 fore any of them had emerged, tenerals of 5. ruhicundulum were 

 found flying in the vicinity of the puddles. Unfortunately I was 

 unable to attend properly to the nymphs and only two emerged, 

 both females. One of them has an exuvia with extremely vestigial 

 dorsal hooks like the Prince Albert specimens, and the imago 

 seems to differ in no way from decisum, while the exuvia of the 

 other is like ohtrusum and the adult is very similar to tjie former 

 specimen, but may be ohtrusum, for I find it sometimes impossible 

 to distinguish between the females of these two species. 



These difificulties with the nymphs led me to a closer study of 

 the imagos, with unexpected results. There seem to be two forms 

 of what we have been calling ruhicundulum in Canada and the 

 Eastern Ignited States. One of these is apparently the same 

 species as the western decisum, and this is the form of which I 

 found tenerals emerging at De Grassi Point. It occurs across 

 Canada from Prince Edward Islan d to British Columbia. The 



3 Loc. cit., p. 525. 



