INSECTS IN GENERAL. 49 



eye, of the same with the tunick and the configurations 

 formed there upon. Fig. 7? represents a portion of the 

 same more magnified. Fig. 8, the eye of Pha. Geom. Grossu- 

 Zariaia, with its peculiar configuration. Figs. 9 and 10, shew 

 the different forms of these configurations, found in the two 

 eyes of the same individual insect in the Pha. homhyx Caja, 

 and Fig. 11, the peculiarity in this respect of Pha. homhyx 

 Crntegata. 



From behind this coloured plaster or tunick, correspond- 

 ing with the socket at each lens, proceed a compact bundle 

 of fibres : these form a case with its base applied to the 

 socket of the lens, and seem to be of a nervous character ; " if 

 so," says the Baron in his Comparative Anatomy, " we may 

 consider each of them as a retina to its particular facet or 

 lens ; but we have still to explain how the light can act on 

 such a retina behind an opake tunick." Fig. 12, shews one 

 of these fasciculi, or conical bundle of nerves, a little re- 

 moved from its lens, and Fig. 13, a series of several of them 

 more magnified, with the lenses in situ : the fasciculi may be 

 observed at their points to come in contact with a membrane 

 running parallel with the lenses. 



This membrane is extremely fine, and penetrated with 

 very minute air-vessels, which produce branches still more 

 minute, passing between the pyramidal fasciculi to the cor- 

 nea ; it is called by Cuvier, from analogy, the choroid. 



Behind this membrane, is a thin expansion of the optic 

 nerve, which is a true nervous chord, perfectly similar to the 

 retina of animals with red blood. It appears that the 

 filaments which form the pyramidal fasciculus or retina to each 

 lens, are produced from this nervous chord, after having 

 pierced the choroid by a multitude of almost imperceptible 

 pores. Fig. 14, displays, entire, one of the component 

 parts of these compound eyes ; a, the lens in its socket ; 6, fe, 



VOL. XIV. E 



