Hoactzin 3 1 9 



the young birds, unless they are quite recently hatched, crawl out of the nest on 

 all fours and rapidly try to hide in the thick brush beyond." When upset into 

 the water, the young are also able to swim rapidly, and even to dive, in order to 

 avoid capture. In the adult birds the claws on the wings have entirely disap- 

 peared, and even the thumb is so poorly developed that no one would suppose 

 its presence in the nestlings. 



From the peculiar characters above pointed out it is little wonder that there 

 has been much speculation as to the relationships of the Hoactzin. The mature 

 bird, as already stated, resembles a game bird, while the nestling has certain 

 characters possessed only by the fossil Arch&opteryx, the oldest known bird. 

 The eggs resemble closely the eggs of Rails, but the abundant skeletal characters 

 separate it not only from the Rails but from most other birds as well. Huxley 

 says that it "resembles the ordinary gallinaceous birds and pigeons more than 

 it does any others, and where it diverges from them, it is either sui generis, or 

 approaches the Plantain-Eaters (Musophagida)." Therefore, while ornitholo- 

 gists are perfectly agreed that the Hoactzin constitutes a distinct order or sub- 

 order, they are by no means of one opinion as to where it shall stand. By some 

 it is placed between the game birds and the Rails, by others, as Dr. Sharpe, 

 between the Pigeons and Rails, while Dr. Gadow refers it as a suborder to the 

 Galliformes, but locating it at the end of that order and therefore near to the 

 Rails. 



