282 [December, 



millefolium iii Surrey. Weise gives Artemisia camjjestris as a food 

 plant, aud it is sometimes locally common on Eujpatorinm cannahinum. 

 It is one of the most abundant of our species throughout the late 

 summer and autumn, and its range extends throughout the Kingdom. 



L. xruginosus was described as a species by Foudi'as [Mon. 

 p. 203], and although Allard makes his L. leevis synonymic with 

 Foudras' L. a;ruginosus, Bedel treats them as distinct species. This 

 author's discrimination, however, does not appear to us to be very con- 

 vincing, i-esting as it does on the difference in character of the apical 

 cilia, which are certainly quite easily abraded ; and in the comparative 

 length of the antennae, which differ sexually. Moreover we have had 

 British specimens, discriminated as L. seruginnsus, returned to us by 

 M. Bedel himself as L. succineus. We therefore cannot escape the 

 conclusion that whether the insect described as L. seruginosus by 

 Foudras was specifically valid or not, the specimens we take in this 

 country on Eupatorium (the food plant of " L. feruginosus ") or any 

 other composite are all of one species — L. succineus, Foudr, 



In bringing to a conclusion these imperfect notes on the British 

 species of the genus Longitarsus, it may not be irrelevant Ijriefly to 

 dwell on some of the more obvious considerations which a survey of 

 the group as a whole occasions. 



Without venturing on any speculation as to the position in the 

 phylogeny of the Halticidos which Longitarsus occupies, from which, 

 if by nothing else, we are precluded by our profound ignorance of the 

 ontogeny of any of its species — our attention is at once arrested by 

 their extreme morphological instability, we might indeed almost say 

 that we appear to have before us a group in nature whose species are 

 still in process of complete differentiation ; and we might further 

 surmise that the specific rigidity which we find in other groups niight 

 only be attained in this by much closer restrictions as regards food 

 plants and consequent conditions, than we find actually to be the case. 

 That many of the species of the genus are dominant in the zoological 

 sense may be inferred by their general abundance and ubiquity ; and 

 that they possess that organic plasticity which enables them to adjust 

 themselves to varying conditions of environment is also evident, and 

 probably the essential factor in such dominance. 



A fui-ther and very striking proof of this organic plasticity is 

 afforded by the state of their wings. 



