464 CROCODILIA CHAP. 



during the night, mostly a little before daybreak. After one 

 half of the eggs has been laid, they are covered up with 

 sand, whereupon the other half is deposited. Then the hole is 

 completely filled up and no visible traces are left behind ; but 

 the mother sleeps upon the nest and thus leads to its discovery. 

 The position of the nest is so chosen that it cannot be reached 

 by moisture from below ; the eggs are most susceptible to moisture, 

 a very slight amount of which causes them to turn bad. 



The shape of the eggs of one and the same clutch varies 

 much, some being elliptical, others cylindrical with rounded off 

 ends. Their size varies from 5 '5 to 9 cm. in length, and 4 to 

 5 cm. in width. The shell is white and glossy, thick and hard, 

 either roughly granular or smooth. They are hatched in about 

 twelve weeks. 



Voeltzkow feels certain that the mother returns to the nest 

 at the proper time in order to dig the young ones out and to 

 conduct them to the water. To test this story he had a nest 

 surrounded with a fence ; the mother returned several times and 

 partly destroyed the fence, which was then replaced by a stronger 

 one. One day, when the young had been hatched, the nest was 

 found to be filled with sand, the shells and one dead little 

 crocodile being at the bottom of the hole. The mother had dug a 

 deep ditch below the fence, but had not succeded in reaching the 

 nest, although she had received and conducted her offspring 

 away. As a rule, when the young are hatched, the sand and the 

 shells are found to be scraped out of the nest. The mother is 

 probably warned by the hiccough-like sound which the young 

 emit while still within the unbroken shell. Voeltzkow heard them 

 piping from the other end of his room, the eggs being covered 

 with a layer of sand two feet high. The sounds were heard 

 when he walked past the nest, or knocked against the box. 

 Possibly the young hear the mother when she retires to the nest 

 to sleep on it, and give her warning to remove the eggs out of 

 the groove. However, they do not break the shell until several 

 days later. 



The hatching is not caused by the rainy season, since it took 

 place a fortnight before the first showers. The " egg-tooth " of the 

 newly hatched young is 0'5 to 0'75 mm. high, bicuspid, and acts 

 like a borer or auger. It is still visible on the tip of the upper 

 jaw, in front of the nose, when the creature is two weeks old. The 



