198 THE LTBELLULINA. 



LIBELLULINA, the members of which are readily distin- 

 guished from all the other Neuroptera by some very 

 striking characters. Their antennae, like those of the 

 May-flies, are very short and tapering, but they are 

 composed of from five to eight joints, of which, how- 

 ever, the first two are the thickest, whilst the re- 

 mainder appear to represent the bristle-like terminal 

 joint of the antennae of the Ephemeras. The head is 

 large and broad, with its sides occupied by a pair of 

 enormous and nearly globular eyes, which are some- 

 times so prominent as to appear nearly pedunculated, 

 whilst in some species they meet upon the upper sur- 

 face of the head, especially in the males. These eyes 

 are beautiful objects under the microscope, from the 

 multitude of minute facets of which they are com- 

 posed, as many as 12,000 of these having been calcu- 

 lated for one species; and it is remarkable that, as 

 pointed out by Mr. Ashton, the upper facets are a 

 good deal larger than the lower ones, a peculiarity of 

 structure which no doubt is in close connexion with 

 the habits and necessities of the insect. Between 

 these eyes, either on the front of the head or on its 

 upper surface, we also find three large ocelli. The 

 mouth, which occupies the whole of the lower front 

 margin of the head, is a most formidable apparatus, 

 admirably adapted to the wants of an animal which 

 captures its insect food on the wing. The upper lip 

 is broad and usually semicircular, concealing the 

 closed mandibles, which are strong horny organs, 

 armed at the apex with numerous acute teeth. The 

 maxillae are also toothed at the tip, but their palpi 

 are short, composed principally of one joint, with a 

 minute one at the base. But the most remarkable 

 portion of the mouth is the labium or lower lip, 



