Embryonic Development of the Crocodile. 67 



have not yet succeeded in securing a specimen of this second 

 species ; my remarks therefore refer exclusively to Cr. nilo- 

 ticus^ Laur. [madagascariensis^ Grandid.). 



This animal is met witli in all sizes, especially numerous 

 on the sandbanks of the Bctsiboka lliver, where, in the space 

 of an hour, in rowing down the river, a hundred and more 

 may be readily observed. The largest which 1 have yet 

 measured was 13 feet in length, though individuals of consi- 

 derably larger size occur. 



Oviposition commences in the latter days of August, and 

 continues until towards the end of Septemb;3r *, after which I 

 found that the eggs all contained embryos. Altogether rather 

 more than one thousand eggs were submitted to examination, 

 derived from about thirty-five batches. In a few cases the 

 number of eggs in the batch could not be exactly determined. 

 The number of eggs in a batch varies between twenty and 

 thirty. 



The nest consists of a pit excavated in the earth to the 

 depth of about a foot and a half to two feet, with partially 

 steep walls. At the bottom of the pit the walls are under- 

 mined, and here the eggs are placed. The floor of the pit is 

 raised slightly in the middle, so that the eggs, as they are 

 laid by the female, roll by themselves into the hoUowed-out 

 places. Very rarely one or two eggs are found lying in the 

 middle of the pit, which may well be taken as proving that 

 the mother does not herself push the eggs into the hollows 

 with her feet, for in that case no eggs would ever be found in 

 the centre of the pit. After the eggs are laid the pit is filled 

 in, and no sign of it can be detected from above. The old 

 crocodile sleeps upon the nest, and this enables the natives to 

 find the eggs, since they follow the tracks of the animal from 

 the water. 



The shape of the eggs is extremely variable, and not even 

 those of the same batch resemble each other completely ; 

 many are elliptical, others cylindrical with rounded ends ; 

 two eggs were pointed at one end. In size they vary from 

 5i to 9 centim. in length and from 4 to 5 centim. in breadth. 

 The shell is white, thick, and hard, sometimes coarsely 

 granular, sometimes smooth. 



Almost all the nests were dug in the dry white sand, a ievr 

 in ground rich in humus, but in such a way that they could 

 not be reached by damp. I must lay especial emphasis 

 on the latter point, since freshly-laid eggs are peculiarly 

 sensitive to wet. More than half the eggs which were 



* Oviposition does uot appear to take place at tlie same time in all 

 localities, since Keller mentions the month of January for Nossi-Be. 



5* 



