38 THE CANADIAN ENTOMOLOGIST. 



nature of Heracleiim in circumscribed areas permit broods to continue and 

 inter-breed for a great many consecutive years. Hence the more apparent 

 reason for environmental forms. And it is not the moth alone which shows 

 variabiHty, the larva exhibits a feature of individual instability with a 

 tubercle plate which has not been observed with others. As only the 

 mature larva has been described, attention may be drawn to the rest of the 

 life-cycle which follows the normal routine. Ova deposited in September 

 winter over and emerge during the last week of May. The early stages 

 of the larva show the characteristic markings ; colour light brownish- 

 maroon, which becomes very dull in the penultimate stage, with longi- 

 tudinal lines white. The dorsal line is continuous, the subdorsal is broken 

 on joints four to eight. This feature places the larva in the grouping to 

 which iiebris and margmideiis belong, and holds with each stage except 

 the last. The tubercles are as usual, well marked and normal for the 

 genus, excepting the accessory IVa, on joint ten. This is small, never as 

 large as IV on the preceding joints, as holds with cerussata for instance. 

 Its uncertain accession is marked in that some specimens have it and 

 some do not, and, further, that an individual may have IVa on one side 

 and not on the other. The thoracic and anal shields are of the usual 

 prominence, and at maturity the colours fade to a soiled, whitish translu- 

 cence. Crochets of prolegs in single row of equal length, hooking out 

 from a broadly U-shaped setting, colour brown, number twenty ; as 

 contrasted to cenissata^ where the number is twenty-two, colour black and 

 the hooks slightly larger. Larvae leave plant for pupation ; July 25-31 ; 

 moths emerge in four weeks. 



A familiarity with the type form, the extreme of variation where the 

 stigmata are black and the primaries darkly suffused, designated by 

 Hampson as aberration No. i. Vol. IX, Catalogue of Phalsenfe, together 

 with the usual intermediate variations, following a three-years' study of 

 Buffalo material, has given the writer a fuller knowledge of harrisii, which 

 seemed necessary before passing finally on two apparently allied forms. 

 One is from California, a species discovered by Mr. F. X. WiUiams, of 

 San Francisco, bred by him from larv?e boring Cirsium occidentale. He 

 kindly forwarded a number of the pupae within their borings where they 

 had changed. One larva had died of a fungous disease, drying into a 

 satisfactory specimen, and was seen to be of the common type, as shown 

 by harrisii and arctivorens, but altogether seemed within the scope of a 

 geographical race of the former. Satisfactory evidence to the contrary is 

 now at hand, and the following name is proposed : 



