THE CATERPILLAR. 



Cyaniris pseudargio- 

 lus ; a, spiracles ; 6, 

 position of extensile 

 organs shown in Fig. 

 35 ; c, opening of ves- 

 icle, which is capable 



of emitting a fluid ; 

 X about 6 (Edwards). 



Other similar extensile organs are occasionally 

 found in different parts of the 

 body in Lepidoptera ; but among 

 butterflies they have been noticed 

 only in some of the caterpillars of 

 the blues, which, when disturbed, 

 extrude a very minute vesicle 

 from a transverse slit on the top 

 of the sev- 

 enth abdcm- 

 segment. 

 was first 



noticed by Guenee* nearly 

 fifteen years ago, but his ob- 

 servations attracted little at- 

 tention until the fact was re- 

 discovered in this country 

 by Mr. Ed wards, f who also 

 noticed and explained the 

 use of still other extensile 

 organs on the next segment of 

 the body in the same cater- 

 pillars [Figs. 34, 35], men- 

 tioned by Guenee, and now 

 known to occur in many blues. 



Fm. 35. Extensile organs 



spines expanded ; 6, with the 

 (pines half withdrawn; both 



Jgji 



The central vesi- 



* Ann. Soc. Entom., France, (4), vii., 665-68(1867). 



t Can. Entom., x., pp. 6,136 (1878). See also Mr. McCook's ob- 

 servations, made independently the same year, in the Trans. 

 Atner. Ent. Soc., vi., pp. 289-91. 



