Pomona College, Claremont, California 149 



female and male so equally and uniformly during the first four or 

 tive moults and with Trochosa during the first six or seven moults, 

 that one is scarcely able to distinguish the sex. Among orb weavers 

 generally, and in spiders of various tribes observed, the change in 

 color is not decided in the male; that is, the young male carries the 

 typical color and general shape of the adult female, the younglings 

 of both sexes after the initial moults resemble each other perfectly, 

 and tend to resemble the adult female. Though the young male of 

 Dictyna p. bears a close resemblance in color and pattern to the 

 adult female. He concludes that when the adult male is more con- 

 spicuous than the adult female, the young of both sexes take after 

 the latter in form and color. On the contrary when the female is 

 more conspicuous the young follow the more modest colors of the 

 male, especially in the earlier moults. When the adult sexes resem- 

 ble each other the young of both favor the common type." 



6. The Adult Thomisidae change color and color pattern 

 according to their environment, but this is not so true of the imma- 

 ture. 



7. ( a ) An adult spider whose ground color is brown, has young 

 whose first ground color is yellow and then later becomes suffused 

 with brown. 



(b) The young of an adult whose ground color is green, is first 

 yellow and then green. 



(c) A gray spider has gray young. 



(d) The black of all spiders, except Latrodectus mactans, is 

 brown black, not pure black. 



(e) The only color found in spiders, due to refracted light, was 

 in the mandibles of Attida?. 



If the color sequences of all spiders were known, it would be an 

 easy task to determine any immature form, but even without this 

 knowledge it is not impossible to determine to what large family or 

 group an immature specimen belongs. Three things have to be 

 considered in the determination: First, that the young resemble the 

 adult in form; second, that the eye placement of the immature is the 

 same as that of its adult; third, the ground color of the immature is 

 the same as in the adult. In this last it may lack in intensity or differ 

 in shade. This may not be true of the first color, but remains true 

 for the second moult. 



