Acentrojjtis. 141 



more positive ones/' I confess I was not quite prepared 

 for the conclusion, that it is " advisable provisionally to 

 separate the forms from different localities/' which sepa- 

 ration Nolcken proceeded to make, as follows : — 



(1) A. niveus. Paris. Female unknown. 



(2) A. Hansoni, Female with ample wings. 



(3) A. Garnonsii. Female wingless (or with rudi- 

 ments ?) . 



(4) A. badensis7 Lake of Constance. Female with 

 short rudiments of wings. 



(5) A. germanicus. Stralsund. Female unknown. 



(6) A. Nevce. St. Petersburg, in the Neva. Female 

 unknown. 



(7) A. latipennis. Both sexes with ample wings. From 

 its colour, shape of wings, &c., certainly a good species. 



Of these seven, he says, at least three may be regarded 

 as certain and well-founded species. 



In the same year (1869) Tengstrom indicated the 

 Finnish form as A. obscuriis, var. of A. Nevce. 



In 1870, Milliere figured A. niveus and latipennis 

 (Iconog. pi. cxv. f. 21, 22) ; and Knaggs inserted A. 

 niveus and latipennis in his ' List of British Lepidoptera.' 

 Finally, Staudinger and Wocke, in 1871, split the differ- 

 ence between Nolcken's three certain and seven possible 

 species, and enumerated the five as foUows : — 



(1) ? niveus, Oliv., Latr. .... Paris. 



(2) Hansoni, Ste., Nolck.=j4. niveus, Ste. 111. England. 



(3) Garnonsii, Curt., Nolck England. 



(4) Nevce, Kol., Nolck St. Petersburg. 



a. ? badensis, Nolck. =niueMS, Hein. . . Lake of Constance. 



b. ? germanicus, Nolck. =:nweMS, Mill. (sp. 



diversa ?) Pomerania. 



c. var. ohscurus, Teng Finland. 



(5) latipennis, Mosch., Mill Sarepta, on the Volga. 



I will make a few remarks upon each of these. And 

 first I may say that the ? prefixed by Staudinger and 

 Wocke to A. niveus is not unwarranted ; for Stephens 

 recognized the insect, not from Olivier's description, 

 which was meagre enough, but from Latreille's abbrevia- 

 tion of that — " blanche, ailes ciliees ; partie superieure 

 de 1' abdomen obscure " — and to identify a species from 

 such a description must be the merest guess-work. 

 Westwood, however, tells us, that Haworth had a speci- 



