No. 597] PRIMARILY UXADAi 



ARIANTS 571 



of foreign intermediate and outcrop in this case is in- 

 teresting, it may or may not be significant. Inhabiting 

 more or less the same region as Callospermophilus, as 

 do western Eutamias, are other spermophiles. They are 

 however speckled or plain colored, little marked for the 

 spermophile group, complements of it, whereas widely 

 separated from it, to the south and east occur sper- 

 mopliiles with sufficient striping to perhaps he considered 

 foreign intermediates between these two northwestern 

 types of spermophile. The above discussion will show 

 how in a single group of mammals, ground squirrels, 

 there exist the various types of variants which have 

 been differentiated above in discussion of fishes and 



The most favorable region for fish development and 

 the center of evolutionary competition for fishes is the 

 tropical coral reef. A great many species have the habit 

 of seeking protection among the projections and crevices 

 which there occur in abundance, and these as a rule are 

 very brightly colored, blue, yellow, green, red, or marked 

 with bold bizarre patterns in endless variety. The 

 theory has been advanced and quite generally accepted 

 that the colors harmonized with the brightly colored 

 corals, etc., over which they occurred, but the fact seems 

 to be that although with occasional spots of color the tone 

 of the reef as a whole is comparatively uniform, these 

 bright-colored fishes are very conspicuous swimming 

 over it, in fact give it a good deal of its brilliant appear- 

 ance. Butterfly fish, wrasses, chromids, parrotfish, etc., 

 belong to this bright, varied crowd. They are safe from 

 all enemies among the labyrinths of the reef and in their 

 evolution have not felt the necessity for concealment." 

 Neutral tones are closer the one to the other than the 

 bright and bizarre, therefore from centrifugal force we 

 should expect, as we find, the bright and bizarre. 



Brilliant birds amidst a luxuriant foliage simulate the 

 conditions and the security of reef fishes and frequently 



