WEAPONS OF ANIMALS 173 



pairs, while the hens usually have a single pair, 

 although sometimes that number is doubled. 



Wing-spurs are present in many birds. The 

 pheasant-tailed jacana or water-pheasant, the spur- 

 winged goose of Africa, and some of the plovers 

 possess a single spur on each of their wings ; while 

 the South American crested screamers are unique 

 in the fact that they are endowed with two pairs. 

 The larger ones attain to a length of an inch and a 

 half, are nearly straight, triangular in shape, and 

 arise from the second joint of the wing, while the 

 smaller ones are curved and broad, and project from 

 the terminal joint of the wing. Although these 

 appendages prove very efficient instruments of 

 offence and defence, yet many birds which are 

 without them will make use of their wings as fighting 

 weapons, the swans and the pigeons being notable 

 examples. 



Even in certain species of frogs we find that the 

 males possess a penetrating armature in the form 

 of spines or spurs. Some of the South American 

 piping-frogs, for instance, develop spinous growths 

 during the breeding season, which arise from their 

 fingers and breasts ; while in certain tree-frogs they 

 project from the anterior surface of their arms. Mr. 

 E. G. Boulenger tells us that : ' In the males of 

 some frogs, such as Eana holsti and Hyla maxima, 

 what at first sight appears to be an innocent rudi- 

 ment of the thumb is in reality a very formidable 

 weapon, for mounted upon the carpus is a long, 

 sharply-pointed bone, which pierces the skin when 

 pressure is made upon it, and when one of these 



