CROCODILIDAE 465 



newly hatched crocodile is of an astonishing size, so that it is rather 

 puzzling to luiderstand liow it was stowed away in the egg. 

 ¥ov instance, an egg of 8 cm. length and 5 cm. width, sends 

 forth a crocodile 28 cm. or 11 inches in length. P]ven at this 

 early age they snap at the finger. 



The egg is covered by a hard shell, within which is a thicker 

 outer and a thinner inner membrane. The " white " is jelly-like, 

 sometimes of a greenish tinge, and is so consistent that it will not 

 flow. The yolk is round, and so large that it nearly reaches the 

 shell-membrane in tlie short diameter. The yolk itself is sur- 

 rounded by a very thin but strong membrane. 



The embryo begins to develop long before the egg is laid. 

 When laid the germ is about 4 mm. long and shows about twelve 

 somites. The cephalic bend begins at the end of the second 

 week, the tail grows longer and the embryo becomes curled up. 

 At the end of the third week it measures 10 mm. in a straight 

 line from brain to vent. The limbs begin to bud in the fourth 

 week. With the sixth week the final shape begins to reveal 

 itself, and is completed at the age of eight weeks ; but a third 

 mouth is necessary to ripen the embryo. 



C. catcq)hrcu-tus is the Common Crocodile of West Africa, 

 from the Senegal to the Congo. In opposition to C. niloticvs 

 it does not enter brackish water. It is easily recognised by the 

 very slender snout, which rather resembles that of the Gavial ; 

 but the mandibular symphysis, although extending to the level 

 of the eighth tooth, does not reach the splenial bones. The 

 premaxillo-maxillary suture on the palate is not transverse, ])ut 

 extends backwards. In conformity with the length of tlie 

 snout the maxillaries meet in the dorso-medial line behind the 

 nasal opening, thus excluding the nasals from the latter. The 

 nuchal scutes consist of two large pairs, almost in contact with 

 the dorsals, six of which form the principal longitudinal rows. 

 The gular and ventral scutes ossify in the adult, hence the 

 specific name. The fingers and toes are slightly webbed. 

 General colour above, dark olive-brown ; yellowish below. The 

 young are olive with large black spots. 



The natives of the Lower Congo catch the crocodiles with two 

 pointed sticks tied together cross-wise, surrounded with entrails 

 by way of a bait. The whole is fastened to a pole or a strong 

 rope and thrown into the river ; and a narrow line, with a fioat 



VOL. Ylll. 2 H 



