1864.] 109 



consideration the European vtllica is the more aberrant form, since it 

 is evidently influenced by the hairy genera with which it is associated. 

 E. virginalis also diff"ers structurally from the European species in hav- 

 ing the antennae nearly simple ; the median nervules longer ; while 

 the third median is nearer the second than in villica. These facts 

 show the importance of studying all the species of a genus which ranges 

 over two continents, in order to properly appreciate the characters of 

 the genus itself, and to see how those characters are apparently swayed 

 and influenced on the one hand by the proximity of other genera in 

 one and the same province ; and on the other, by the strong influence 

 of a corresponding geographical province . 



Thus in illustration : — the American genera of this sub-family are 

 more generally white and finely scaled, i. e. Callimorplia, Leucarctia^ 

 Seirarctia, Halesidota^ Ecpantheria and allies, and Eiichsetes, while 

 in Europe they are more prevalent red and brown, and wooly genera, 

 such as Oneogyna and the numerous species of Arctia. 



However, this state of things is reversed in the genus Callarctia 

 ( Chelojiia Grodt.) Here the Californian species is pilose and the abdo- 

 men is slender, while the European species are finely scaled and have 

 obtuse abdomens. 



A single specimen from San Francisco, Cal., now in the Mus. Comp. 

 Zoijl. was collected by A. Agassiz. 



Herrich-Schaeff"er figures (Lep. Exot. Sp. Nov. p. 72, fig. 464) Ple- 

 refes gutfafa in illustration of Boisduval's Agarista guttata (Lep. Cal. 

 p. 48, 1852). The last named author gives us too meagre a descrip- 

 tion of the species for us to know whether it is a Zygoenid or not. 

 H.-Scha3fi"er's figure represents a species so closely allied to E. virgina- 

 lis as to lead us to suspect that it is but a variety of that species. It 

 seems to difiier in having dark secondaries, with a single light dot, but 

 otherwise answers to Boisduval's description of E. virginalis. 



PLATARCTIA*- nov. gen. 

 Head prominent; front square broad, moderately pilose, hairs on the 

 front margin converging to a point. Palpi long, pointed, porrect, ex- 

 tending one-half their length beyond the front. Antennas moderately 

 pectinated, in 9 subsimple, serrated, the teeth terminating in setse. 



'^lAarvs broad, Arctia. 



