26 



Genus YII. COLIAS. 



Fabricws. 



Colias, Linn, Colias, a surname of Yenus, from a promontory of Attica, 

 at which she was worshipped. 



This genus is met with in almost every part of the world except Australia, 

 New Zealand, the East and West Indian Islands, and perhaps Central Africa. 

 It occurs all over Europe. In Asia it is found from Nova Zembla and 

 Siberia to the Southern parts of India ; in Africa it occurs from Egypt and 

 Abyssinia to the Canary Islands and a^ain at the Cape of Good Hope ; in 

 America from Grinnel Land and Boothia Felix, to Tierra del Fuego ; and it 

 is also found in the Sandwich Islands. It is, however, very much confined to 

 the mountains in the inter-tropical countries. On the mountains of Europe, 

 some species are found almost up to the regions of perpetual snow ; and on 

 the Himalayas, one species occurs at the great elevation of 17,000 feet. 



The prevalent colour of all the species is yellow or orange, sometimes 

 verging to white in the females, sometimes, as in the most northern species, 

 to a greenish hue. Near the centre of the hind wings is a deep orange spot. 



The antennee are short and rather thick, and like those of Gonepterex, 

 of a reddish colour. 



The males exhibit a character, often overlooked, which serves well to dis- 

 tinguish the species. It is a kind of a glandular sac placed upon the 

 anterior edge of the hind-wings near the base. It is large in Edusa, small 

 and lenticular in Myrmidone, and wanting in Hyale and Chrysothome. 



About thirty species are known, nine of them occurring in Europe. 



Our two British species are both noted for their periodic appearance. 

 These periods were supposed to be influenced by the eggs or chrysalids lying 

 dormant, but our knowledge of this genus will warrant us in considering all 

 these suggestions as arbitary, and unsupported by facts. It is possible, that the 

 females may occasionally forsake the ordinary habit of the species of flying 

 up and down one or two clover fields for hours or indeed for days together, 

 and fly, as they can do, swiftly across the country, re-enforced by a few 

 immigrants from the Continent, laying a few eggs here and a few eggs there, 

 in the various clover fields over which they pass ; and that the caterpillars 

 in a favourable summer feed up rapidly, escaping their worst enemy in this 

 climate, — mould ; and so the perfect insects might be found, earlier or later, 

 according to the climate, some inland, and large numbers in those coast dis- 

 tricts, in which they usually occur. 



Some species of the genus have been observed at great distances from land. 

 Mr. Charles Darwin names an instance worth quoting. " One evening, when 



