PAPILIONIN.E. 193 



spine-like tubercular processes ; second (protliorcacic) segment containing 

 dorsally an exsertible forked glandular Uesliy organ, emitting a pene- 

 trating odour. 



1>UPA. — Very variable in shape, but usually more or less curved or 

 bent backward superiorly, and angulated ; head usually more or less 

 bifid, but sometimes sub-truucatt', blunt, or rounded ; back of abdomen 

 often tuberculated. 



This Sub-Family is very distinct from the rierincv, the approach 

 made to the latter by the aberi'ant Farnassius ^ being very slight, and 

 such genera of Ficrincc as Mesapia, Gray, Davidina, Oberth., and Sti/.x; 

 Stand., not exhibiting any structural affinity, but only a superficial 

 resemblance to Farnnssius.'-^ The salient features in the Fapilionince 

 are, as regards the perfect insects, the arrangement of the disco-cellu- 

 lar and radial nervules of the fore-wings, making the lower radial appa- 

 rently a fourth median nervule ; the development of the interno-median 

 nervule and of the free internal nervure in the same wings ; and in 

 the hind wings the hollowed inner-margin (with absence of the internal 

 nervure), and formation of a small prediscoiclal cell by the branched 

 precostal nervure ; while the first pair of tibite bear on their inner edge 

 a conspicuous process or spur. The caterpillars stand alone among 

 those of the entire Sub-Order^ in possessing the strongly scented 

 exsertible fleshy organ or " tentacle " in the neck, which is instantane- 

 ously protruded and directed vibratingly towards any part where the 

 insect may be touched. This organ is usually of some red or crimson 

 tint, but sometimes blue or yellow ; and its sudden appearance, mena- 

 cing motion, and penetrating disagreeable odour, combine to make its 

 possessors alarming and repulsive to their foes. 



Painlio, with some 400 species, is beyond comparison the domi- 

 nant genus of the Sub-Family, extending throughout the globe, but 

 very poorly represented in the Palasarctic, Nearctic, and Australian 

 Eegions. The other twelve genera, including Ornithoptcra (about 

 twenty species), together muster only sixty-one species, and of these 

 Farnassius alone counts twenty-three, five of the genera being mono- 

 typic. In curious contrast to its poverty in species of F^ipilio is the 

 richness of the Palfearctic Piegion in generic forms, Scricinus, Thais, 

 Hypernmestra, Doritis, and LiieMorJia being all peculiar to it, and 

 Farnassius peculiar except for two or three North-American forms ; 



1 See Doubleday, Gen. Diurn. Lep., i. p. I (1846). The singular Turkestan genua 

 Hypermnestra, however, has in outline and hind-marginal markings of the wings, and espe- 

 cially the pattern and colouring of the under side of the hind-wings, a striking resemblance 

 to Anlhocharis and the Daplidicc group of Pieris. 



- It is worth mention, however, that the chrysalis of Zegris (a Southern Pakearctic 

 genus close to Anthocharis) is enclosed in a delicate silken web after the manner of that of 

 Parnassius. 



3 The whole Order Lepidoptera is known to yield only one other genus, viz., Bicranura 

 [Ccrura) among the Bombyces, whose larva; have an equally developed organ of this re- 

 markable description ; and in these the organ is double instead of merely forked, enclosed 

 in special sheaths, and occupies the posterior instead of the anterior end of the body. 



VOL. III. N 



