No. 3. 1 SEXUAL SELECTION IN SPIDERS. 141 



a remarkable confirmation of Mr. Darwin's views that gayly 

 colored plumes are developed in the male bird for the purpose 

 of attractive display in the breeding season." * 



In the gallinacese of North America there are some thirty 

 species of partridges and grouse, in which the tail is short or 

 only moderately long — not longer than the wing. In fourteen 

 species there are head and neck plumes, which are, evidently, 

 not protective. To show that these cannot be due to the 

 superior vitality of the male, we may mention that in six of 

 these species, plumes are found on the top of the head in both 

 sexes. 



The Distribution of Accessoin/ Plumes in Humming- Birds Refutes 

 Mr. Wallace's Theory. 



The pectoral muscles reach their highest development in 

 the humming-birds, the diurnal birds of prey and the swallows, 

 and we may, therefore, fairly use these groups to test Mr. Wal- 

 lace's explanation of breast plumes. In the swallows and birds 

 of prey we find no such appendages, in spite of their further 

 claim to them, on the ground of great vigor and activity. As 

 to the humming-birds, we find in the genus Aglseactis six 

 species with more or less developed breast-plumes, which are 

 also found in nine other species, scattered through different 

 genera — in all, only fifteen species out of four hundred and 

 twenty-six ; while we find in fifty-six species the lengthened 

 and modified tail-feathers, which, accordingf to Mr. Wallace's 

 view, should be peculiar to the galliuacea;. 



Again there are elongated feathers from the throat or from 

 the side of the neck in thirty-five species,| while seventeen have 

 crests from the top of the head, and seventeen, downy puffs 

 from the tarsi. 



From this very brief survey of the family we see that, con- 

 trary to what we should expect from Mr. Wallace's theory, 



* Volume I, p. S3P. 



f Loddigesia mirabilis has the tiiil about three times as loug as the hody. Similar 

 modifications are found in the genera Sappho, Cynanthus, Leshla, Steganura, Discura, 

 Gouldia, et aL 



I Among the most remarkable of this ivonderful family are the nine spee'es of co- 

 quettes (Lophornis), which have elongated feathers, with metallic tips, springing from the 

 sides of the neck ; some have also beautiful crests. 



