2o8 THE BIOLOGY OF BIRDS 



B. Illustrations of Sex-Characters. — Convenient surveys 

 of sex differences are to be found in Darwin's " Descent 

 of Man " and Cunningham's " Sexual Dimorphism." 

 Among Mammals one recalls the gorilla's sagittal crest, 

 the mandrill's enormous canines, the elephant-seal's nasal 

 proboscis, the lion's mane, the narwhal's tusk, the stag's 

 antlers, the duckmole's spur. Among Birds one recalls the 

 peacock's tail, the wing-feathers of the Argus Pheasant, 

 the decorations of birds of paradise and humming-birds, 

 the tail of the lyre-bird, the neck-feathers of the ruff, the 

 cock's spur, the great bustard's inflatable throat pouch. 

 In some parrots the female is red and the male green ! 

 Among reptiles there are a few cases like the erectile dorsal 

 crest of Anolis cristatus and the bony horns of some 

 chamaeleons. Among amphibians there are the dorsal 

 crests of some newts, the swollen first fingers of frogs and 

 toads, the resonating sacs of some frogs. Among fishes, we 

 recall the salmon's hooked lower jaw, the brilliant colouring 

 of the male dragonet, the " claspers " of Selachians. Among 

 Invertebrates, there are well-known contrasts between the 

 sexes in the Argonaut, in the Giant Japanese crab, in many 

 spiders, in Dynastid and Lucanid beetles, and in many 

 Lepidoptera. 



In most cases the positive character is on the male side. 

 He has an extra something which the female does not possess 

 in a developed state, if at all. It is important therefore to 

 recall two or three examples of the converse. The females 

 of the frog genus Nototrema have a pocket on the back into 

 which the male pushes the eggs. So far as we know the 

 marsupium of Marsupialia is never more than a rudiment in 

 the males. In the Red Necked Phalarope the female is the 

 more decorative bird. The same is true of the Painted 

 Snipe {Rhyiichcea capensts), a bird widespread in Ethiopian 

 and Indian regions. It is the female who is the handsomer, 

 and it is interesting to notice that the male, as in the 

 case of Phalaropes, performs most of the duties of 

 incubation. 



In some cases the female bird is the larger, and this may 



