14 PECKHAM. [Vol. 1, 



a thick, web-like covering, with their cocoons, until the eggs 

 are hatched — that is to say, all the species of this family 

 have covered nests. Many of these covered nests are occupied 

 by dull-colored females, the males of the same species being 

 showily attired. The same is true, to a great extent, among 

 the 'Fhrnnisidx, where the females, often protectively colored, 

 remain near the eggs in a covered nest. The protectively col- 

 ored Lycosidas, it is true, have practically open nests, as they 

 usually carry the eggs about with them. In other families the 

 habits vary, some leaving the eggs to their fate as soon as the 

 cocoon is formed, while others give it much or little attention, 

 as the case may be. A general survey of the facts shows no 

 relation between color development in the females and their 

 nidifying habits, and it is higlily probable that in spiders, as in 

 birds, the color was developed prior to the formation of these 

 habits. 



We must, then, seek further for an explanation of sexual 

 coloring in spiders, since here we have present to account for 

 it neither special vitality on the part of the male, nor need of 

 protective coloring, while nidifying, in the female. 



MOULTING HABITS. 



There is no group of facts that brings out the remarkable 

 similarity between birds and spiders in color development 

 more prominently than that which is gained from a study of 

 the moulting habits of the two classes. In spiders, as in birds, 

 the young very often differ from the adults, and in many spe- 

 cies where the sexes differ when adult, the male being the 

 brighter, they are alike until they reach maturity, when the 

 male, along with his sexual development, acquires his brilliant 

 color. Cuvier formulated, under several rules, the various 

 changes that the plumage of birds undergoes from the nestling 

 to the adult. These rules were extended by Blytli ; and Dar- 

 win, in Tlie Descent of Man, not only amplified and added to 

 them, but also submitted them to a thorough analysis and dis- 

 cussion in order to discover the causes of the phenomena. In 



