SPIDEBS AND MITES. 207 



from its thinness is semi-pellucid, but the eyes transmit 

 the light with brilliance, not, however, as if they were 

 simple round holes, because you can discern very mani- 

 festly a hemispherical glassy coat, by which it is refracted. 

 It is, however, when we examine the forehead of a living 

 or recently killed spider, that we see the eyes to advan- 

 tage. In this example of the same species (Clubiona 

 atrox), you see them, like polished globes of diamond, 

 sunk into the solid skin of the head. Their form is 

 unimpeachably perfect, and the reflection of light from 

 their surface most brilliant. 



EYES OF SPIDER. 



The arrangement of these lustrous eyes is worthy of 

 attention. They are generally eight in number in Spiders, 

 but their relative position varies so much, as to afford 

 good characters by which naturalists have grouped them 

 in genera. In the Clubiona which we have been examin- 

 ing, they are placed in two nearly straight transverse rows 

 on the forehead ; but as this surface is convex, it follows 

 that the axis of every eye points in a different direction 

 from that of its fellows. In Epeira, on the other hand, 

 represented by our great Garden Spider, so commonly seen 



