The Biology of the Crocodilia 41 



mouths wide open it is quite possible that these 

 birds may pick off the worms that are often found 

 within. It is also possible that the alertness of 

 these birds to danger may serve as a warning to 

 the crocodiles with which they associate. 



According to Voeltzkow these crocodiles dig 

 caves of thirty-nine to forty feet length in the 

 banks of the streams they inhabit, into which they 

 retire on the approach of danger. The caves open 

 under water and slope upward towards the surface 

 of the ground where a few small air-holes are 

 found. The natives locate the caves by means of 

 the air-holes and dig out the hidden animal, first 

 stopping up the entrance. 



In Madagascar the eggs are laid in August and 

 September and hatch in about twelve weeks; 

 they are laid at night, usually shortly before day- 

 break. From twenty to thirty eggs are laid in 

 one nest, which is merely a hole dug in the dry 

 sand. As was said in connection with the Florida 

 alligator, the habits of the two animals are quite 

 different in this respect, — the moisture that is so 

 important in the one case is fatal to the embryo 

 in the other. When the eggs are laid the nest is 

 filled in with sand so that there is nothing to indi- 

 cate its position except that the female crocodile 

 is in the habit of lying on the spot where her eggs 

 lie buried. 



Like the alligator the young crocodile makes a 

 squeaking noise shortly before hatching and the 



