86 Lloyd's natural history. 



Imago.— Large, or very large (rarely less than an inch and a 

 half in expanse, and occasionally attaining the dimensions of a 

 foot in expanse). Antennae short, strongly bipectinated, espe- 

 cially in the males ; mouth parts rudimentary ; body stout, rarely 

 as long as the hind-wings, and frequently only half as long ; 

 wings broad, cells usually closed ; fore-wings sometimes more or 

 less pointed, produced at the tip ; hind-wings with no frenulum, 

 with one sub-median nervure, and sometimes tailed. All the 

 wings have usually a large central ocellus, generally round, but 

 sometimes irregular in shape, sometimes opaque, and some- 

 times perfectly hyaline ; legs short and stout, without spurs. 



GENUS ATTACUS. 



AUacus, Linnaeus, Syst. Nat. (ed. xii.), i. (2), p. 809 (1767); 

 Hiibner, Verz. bek. Schmett., p. 155 (1822?); Walker, 

 List Lepid. Ins. Brit. Mus., v., p. 1200 (1855). 



Hyalophora, Duncan in Jardine's Nat. Libr., Exot. Moths, 

 p. 124 (1841). 



This genus includes the largest Lepidopterous insect known, 

 the great Atlas Moth of India {Atiacus atlas, Linn^us), the 

 largest specimen of which, in the British Museum, measures 

 eleven inches and three quarters across the tips of the 

 wings, though most specimens measure only eight or nine 

 inches in expanse. It is very variable both in size and 

 colouring, apart from the numerous more or less well-marked 

 local forms, which some entomologists regard as distinct 

 species. The costa of the fore-wings is arched, and the tip 

 forms a rounded hook, the hind margin below forming a very 

 obtuse curve. Body very short, less than half as long as the 

 hind-wings, which are much produced towards the anal angle ; 

 the hind margin forming a very long curve. 



