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THE POPULAR SCIENCE MONTHLY. 



A scale-like covering, which is fixed and immovable, covers the eye 

 of the serpent, as shown in Fig. 4, and gives to it, as Prof. Nicholson 

 vividly expresses it, the " peculiar, stony, unwinking stare " for which 

 they are remarkable, and which, when they are enraged, becomes 

 intensely fierce. 



Fig. 10. 



Guinea Rock-Snake. 



This covering is evidently transparent, as the animal distinguishes 

 forms, but in the cast-off skin it is translucent only. Behind the eye- 

 ball is a lachrymal gland, with a duct which conveys tears to the 

 membranes of the eye. By this means they are kept moist. A con- 

 duit connects the eye-cavity with the olfactory opening, and, should 

 the creature shed tears, it would be through that opening, not directly 

 from its eyes. 



In common with other animals, serpents have some habits and 



