THE SUBFAMILY rAriLlONINAK. 1223 



Thaitcs ruininiana, has been found in tlie tertiaries of Aix in southern 

 France. 



The early stages. The eg<is of the swallow tails are always suhspher- 

 ical and nearly destitute of seulpturing, resenihling the Pamj)hilidi, or cer- 

 tain Sphingidae, hut those of the Parnassidi are covered with minute pits, 

 and thus strikingly similar in surface sculpture to the eggs of Lycaenidae ; 

 and not improbably still different forms of eggs may be found in other 

 genera. 



The juvenile caterpillars of the swallow-tails are peculiar for the long 

 bristles arranged on fleshy tubercles, many of the latter compound, and 

 larger at tlie extremities of the body than in the middle. Those of the 

 Parnassidi are described below. The mature caterpillars of all the sub- 

 family look very differently and may be distinguished by the possession of 

 osmateria, — a strongly scented, bright colored, viscid, forked tentacle which 

 is wholly concealed at ordinary times but is suddenly extruded if the ani- 

 mal be offended or alarmed. 



When we consider [says Wallace (Nat. selection, 135)] this singular apparatus, 

 which in some species is nearly half an inch long, the arrangement of muscles for its 

 protrusion and retraction, its perfect concealment during repose, its blood-red color, 

 and the suddenness with which it can be thrown out, we must, I think, I)e led to the 

 conclusion that it serves as a protection to the larva, by startling and frightening away 

 some enemy when about to seize it, and is tlius one of the causes whicli has led to the 

 wide extension and maintained the permanence of this now dominant group. Those who 

 believe that such peculiar structures can only have arisen by very minute, successive 

 variations, each one advantageous to its possessor, must see, in the possession of such 

 an organ by one group, and its complete absence in every other, a proof of a very 

 ancient origin and of very long continued modification. 



It should be remembered that according to Boisduval (Nouv. ann. mus., 

 1833, 261) the larva of one of the Phalaenidae, Urania, "fait sortir a 

 volonte deux cornes retractiles roses, placees sur le premier anneau." An 

 argument of this kind which will apply to one will apply to the other. 



According to Westwood, the osmateria of Ornithoptera are "contained 

 in a fixed bifid sheath," but this statement requires corroboration, for it is 

 founded upon Horsfield's illustrations, which may perfectly well be other- 

 wise interpreted. 



The caterpillars are naked, or armed only with fleshy prominences or fila- 

 ments, and are generally brightly colored, often provided with a few large, 

 eye-like spots, or streaked with patches of oddly mingled colors, giving 

 them a grotesque appearance ; the anterior segments of the body are en- 

 larged in some species, while in others the whole body is equal ; the head 

 is partially covered by the first thoracic segment. Their habits are 

 usually solitary, but in one South American group tiie caterpillars live on 

 Aurantiaceae, in societies of one or two hundred individuals, and when 

 young, feed side by side in rows, and the caterpillars of one of our New- 

 England genera are social during at least a part of their life : excepting a 



