238 EVENINGS AT THE MICROSCOPE 



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 in the cen- 

 tre of its perpendicular web, on shrubs and in corners of 

 our gardens the four middle eyes form a square, and the 

 two lateral ones on each side are placed in contact with 

 each other. 



It is interesting to remark that their arrangement is 

 not arbitrary, but is ancillary to the varying instincts and 

 wants of the different kinds. On this subject I will quote 



EYES OF SPIDER 



to you what Professor Owen says: ' l The position of the 

 four median ones is the most constant; they generally in- 

 dicate a square or trapezium, and may be compared with 

 the median ocelli in hexapod insects. The two, or the two 

 pairs of lateral ocelli, may be compared with the compound 

 eyes of insects; the anterior of these has usually a down- 

 ward aspect, while the posterior looks backward; the va- 

 riety in the arrangement of the ocelli of Spiders always 

 bears a constant relation to the general conformation and 

 habits of the species. Dujes has observed that those Spi- 

 ders which hide in tubes or lurk in obscure retreats, either 



