PEOTECTIVE RESEMBLANCES-DIMORPHISM, ETC. 59 



Spiders are often protectively coloured ; many ex- 

 cellent examples are given by Elizabeth G. Peckham. 1 

 One of the most remarkable is Ccerostris mitralis, from 

 Madagascar, which sits motionless on a branch and 

 resembles a woody knot. Its appearance is shown in 

 fig. 15. A common Wisconsin spider, Epeira prompta, 



FIG. 15. Cceroslris mitralis in proaie; FIG. IS.Speir 



from Peckham ; after Vinson. lichen - covered" tree"- trunk ; from 



Peckham. 



generally rests on the branches of cedar bushes, and 

 closely resembles lichen (see fig. 16). Spiders are 

 especially relished by insectivorous animals, so there 

 is every reason for the faithfulness of these resem- 

 blances. In many other cases, however, the resem- 

 blance is chiefly aggressive, enabling the spider to 

 approach its prey. 



1 Occasional Papers of tJie Natural History Society of Wisconsin, 

 vol. i. 1889, Milwaukee, pp. 61 et seq. 



