HO W THE MASK IS MADE. 185 



eyes, which resemble little mammillary protuberances, are situ- 

 ated above and outside of the vizor. On the animal's back, 

 where the belly joins the thorax, do you observe those four 

 little sheath-like or scabbard-like tongues? The extremity 

 of the body, the tail, is marked by three conspicuous triangular 

 points, lying close to the opening, through which the water 

 enters and issues, as if it were 

 alternately sucked in and 

 poured out by a piston. This, 

 you must understand, is the 

 respiratory apparatus. (See 



FIG. 40. Larva of the FIG. 41. Larva of 

 Fig. 40.) Libellula depressa. \hz Agarion vtrgo. 



Well, then, what is the name of this most singular creature, 

 this masked knight ? 



It is the larva of the Lfreiluia depressa; the dismal envelope 

 whence will issue the gaudy Dragon-fly. Listen to a graphic 

 description of the mask you are looking at : 



" Conceive your under-lip to be horny instead of fleshy, and 

 to be elongated perpendicularly downwards, so as to wrap 

 over your chin and extend to its bottom ; that this elongation 

 is there expanded into a triangular convex plate attached to 

 it by a joint, so as to bend upwards again and fold over the 

 face as high as the nose, concealing not only the chin and the 

 first-mentioned elongation, but the mouth and part of the 

 cheeks ; conceive, moreover, that to the end of this last- 

 mentioned plate are fixed two other convex ones, so broad as 

 to cover the nose and temples ; that these can open at plea- 

 sure transversely, like a pair of jaws, so as to expose the nose 



