YOUNG CROCODILIANS IN CAPTIVITY. 175 



Jo not actually coalesce in the middle line, nor are they 

 quite opposite one another. The mesial portions of the 

 marks are about half an inch in width. They curve out- 

 wards and backwards, and taper somewhat on the sides, 

 where they slope very obliquely backwards. The neck has 

 a few dark patches on its shields. The last two-thirds of 

 the tail is serrated. On the anterior superior third are 

 three dark bars. The remaining and laterally compressed 

 two-thirds has regular bars running downwards and 

 slightly backwards. Irides dull ochre. There are four 

 paired transverse series of nuchals, and eighteen trans- 

 verse series, the broadest with ten shields. Colouration 

 fades in every species with growth or age. By the time 

 the Caiman reaches a length of two feet the dorsal marks 

 have become almost obliterated. The upper surfaces are 

 of a dark olive colour, head very dark, the sides and tail 

 yellowish; the latter still shews some bars. Under 

 surfaces a pale grey on the sides, becoming yellow in the 

 centre. They cannot be trusted with smaller specimens. 

 A rough-eyed Caiman, 28 inches long, killed and partly 

 swallowed a small one of the same species ten inches long. 

 On being handled it makes frequent and determined 

 efforts to bite, at the same time hissing and uttering its 

 peculiar grating cry. 



I have not had opportunities of determining, satisfac- 

 torily, whether age or growth is more responsible for 

 colour fading. Most crocodilians of two and a half or 

 three feet have already assumed, or are assuming, the 

 sombre hue of adult specimens ; the earliest change 

 noticeable being a darkening of the ground colour, 

 thus diminishing the contrasts. In the Mississippi 

 alligator less change is required, it is already almost 

 black. The only portions to fade are the dark yellow 

 bands. 



