EXTERNAL ANATOMY OF INSECTS. 501 
on their inner side, as it were, taken out of them; so 
that they more than half surround the antenne, before 
which is the longest portion of them. An approach 
to this shape is more or less observed in the darkling- 
beetles (Zenebrio, &c.); but in these the sinus is not so 
deep. I may under this head observe, that in those 
Mantide that represent dry leaves, and some others, 
these organs usually terminate in a spine’. 
Though not distinguished by the beauty and anima- 
tion that give such interest to the eye of vertebrate ani- 
mals, and exhibiting no trace of iris or pupil, yet from 
the variety of their colours the compound eyes of insects, 
though most commonly black or brown, are often very 
striking. Look at those of one of the lace-winged flies 
that commit such havoc amongst the Aphides®, and it 
will dazzle you with the splendour of the purest gold, 
sometimes softened with a lovely green. The lenses of 
those of Xenos blaze like diamonds set in jet*. You 
have often noticed the fiery eyes of many horse-flies 
( Tabanus, &c.) with vivid bands of purple and green 4. 
Others are spotted ©; and Schellenberg has figured one 
( Thereva hemiptera)*, that exhibits the figure of a flower 
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 
* Stoll Spectres, &c. t. iv. f. 14. t. x. f. 38, &e. 
> Vou. I. p. 264—. © Linn. Trans. ubi supr. 
* Schellenberg Mouches, ¢. xxvii. f. 1, 2. a, d. 
© Abide t. ixefea. a f Ibid. t. ii. f. 2. a 
