192 



ZOOLOGT, 



of the Order HemtpterA, it is bent downward to the breast, 

 as in the genera Cicada, Nepa, Notonecta, CimeXy and re- 

 markably in some of the Curculionce. The Tongue in some 

 kinds is taper and spiral, as in Butterflies, in others fleshy 

 and retractile, resembling a proboscis ; and in flies it is 

 tubular. 



In most Insects the eyes are placed on each side of the 

 head, generally two in number, Spiders have six or eight, 

 and Scorpions six. They possess no eye-brows, but the ex- 

 ternal tunic of their eyes is hard and transparent, like a 

 Watch-glass ; their eyes have no external motion, except in 

 the genus Cancer : the eyes in most kinds are compound, at 

 least their exterior coat or cornea is so, which when 

 Tiewed with a microscope, appears composed of a number of 

 •eparate hexagonal convex lenses ; these have been supposed 

 each to act as a separate eye ; yet it is not easy to discover 

 the use of the immense number with which some are pro- 

 Yided, as the head of the Dragon Fly is computed to be 

 furnished with not fewer than twenty-five thousand of the 

 separate lenses or eyes. On the top of the heads of many 

 species, are three small, smooth, hemispherical dots or glo- 

 bules, resembling eyes, these are situated between the real 

 eyes, their use and nature is not clearly ascertained, the? 

 were called by Linneas Stemmata. 



Whether Insects are possessed of Brain, continues to be 

 ?iu object of dispute, with the learned, in this branch of 

 anatomical knowledge, however most kinds are furnished 

 with a medulary thread, which passes through their whole 

 extent ; but that this is analogous to the brain and spinal 



