xvii THE CROCODILE 219 



As in the case of whales, the size of crocodiles has 

 been greatly exaggerated. In the rivers and lakes of 

 East Africa, and in the Nile itself, a crocodile measuring 

 fifteen feet, from the snout to the tip of the tail, is 

 considered a big specimen. 



The senses of sight and hearing in these wary reptiles 

 are remarkably acute. No one knows the age to which 

 they live. Crocodiles lay eggs, sometimes to the num- 

 ber of three score. The eggs are white, oval, and 

 possess hard shells ; they are laid and well concealed in 

 sand, out of reach of moisture, for this causes them to 

 decay quickly. 



The Varanus lizard or monitor is fond of crocodile 

 eggs and is an adept at finding them in the sand. This 

 lizard attains a length of five feet and is common in 

 the upper reaches of the Nile : it lives in the trees and 

 in water, and generally plunges into the stream when 

 disturbed. Varanus lives largely on fish and no doubt 

 captures and eats small mammals and birds : it uses the 

 long heavy tail as a whip, especially when driven into a 

 corner. Most visitors to the Zoological Gardens, London, 

 have seen the monitor critically examine an egg with its 

 forked tongue, then take the egg into its mouth, 

 crush it, and after swallowing the contents eject the 

 shell. Monitors are very critical as to the quality of 

 an egg. 



It was thought probable that the crocodiles in the 

 Victoria Nyanza were carriers of trypanosomes. This 

 suspicion proved to be groundless. The red capsules 

 of the crocodile are elliptical, like those of birds, and are 

 easily identified with the aid of a microscope : during 

 the investigation of sleeping sickness this fact enabled 

 the observers to determine from an examination of 

 tsetse flies whether they had been feeding on crocodiles 

 or not. 



The story, related by Herodotus, concerning the cro- 

 codile and the bird Trochilus has always excited 

 curiosity in the minds of ornithologists interested in the 



