EXTERNAL ANATOMY OF INSECTS. 503 



painted in red on a black ground. These colours and 

 markings are all most vivid and brilliant in the living 

 insect, and often impart that fire and animation to the 

 eyes for which those of the higher animals are remark- 

 able. Take one of the large dragon-flies that you see 

 hawking about the hedges in search of prey, examine its 

 eyes under a lens, and you will be astonished at the bril- 

 liance and crystalline transparency which its large eyes 

 exhibit, and by the remarkable vision of larger hexagons 

 which appear in motion under the cornea, being reflect- 

 ed by the retina — all which give it the appearance of a 

 living eye. This moving reflexion of the hexagonal 

 lenses in living insects was noticed long since in some 

 bees (Nomada F., Ccelioxys Latr.) a 



Compound eyes differ greatly in their size. In some 

 insects, as Atractocerus, the drone-bee, many male Mus- 

 cidce, &c, they occupy nearly the whole of the head ; 

 while in others, as numerous Staphylinida, Locusta 

 Leach, &c, they are so small as to be scarcely larger 

 than some simple eyes of spiders: and they exhibit 

 every intermediate difference of magnitude in different 

 tribes, genera, and species. 



Under this head I must say something of the Canthus 

 of the eye ; by which I mean an elevated process of the 

 cheek, which in almost all the genera of the Lamellicorn 

 beetles enters the eye more or less, dividing the upper 

 portion from the lower. Though usually only & process of 

 the cheek, yet in the Scarabceida the whole of that part 

 forms the canthus b . It only enters the eye in the Ru- 

 telidcSy Cetonidce, &c. ; it extends through half of it in 



* Mori. Ap. Angl i. 148. b Plate XXVII. Fig. 4. h'. 



