INTKODUCTION. 



distance from the antennae. Under the cornea, which varies in 

 convexity, is found a transparent, rather hard, and nearly globular 

 body, which is the true crystalline resting on a sort of lens, which 

 represents the vitreous body. This vitreous body is enclosed in an 

 expansion of the optic nerve. Besides these, there is a pigment, 

 most frequently red-brown, sometimes black, or blood-red. The 

 organisation of these eyes is analogous to the eyes of fishes, and 

 their refractive power is very great. 



"With these insects can only see such objects as are at a short 

 distance. Of what use then can stemmata be to insects also pro- 

 vided with compound eyes ? It has been remarked that insects 

 having this arrangement of eyes feed on the pollen of flowers, and 

 it has been surmised that these stemmata enable them to distin- 

 guish the parts of the flowers. 



The antennas, commonly called horns, are two flexible appen- 

 dages of very variable form which are joined to different parts of 

 the head, and are always two in number. The joints of which 

 they are made up have each the power of motion, and enable the 

 insect to move them in any direction. 



The antennae consist of three parts, the basal joint, commonly 

 distinguished by its form, length, and colour ; the club formed by 

 a gradual or sudden thickening of the terminal joints, of which 

 the number, form, and size present great variations ; lastly, the 

 stalk formed by all the joints of the 

 antennae, except the basal one when 

 no club exists, and in case of the 

 existence of a club, of all those be- 

 tween it and the basal one. 



We give as examples the anten- 

 nae of two beetles, one of the genus 

 Asida, the other of the genus Zygia 

 (Figs. 3 and 4). 



Insects for the most part, while 

 in repose, place their antennae on 



their backs, Or along the sides of the Fig 3 _Antenna of a 



head, or even on the thorax. Others 8 * ec ' ie8 of Asida " 



are provided with cavities in which the antennae repose either 



wholly or in part. 



Fig 4. Antenna of 



