SUB-CLASS RATIT^— ORDER RHEIFORMES. 



we know less, but though its bones are not so often discovered as tliose of 

 the moa, its eggs, uneartlied from the tombs of buried chiefs, are not un- 

 frequently found 



The Ratite Birds, as these great flightless creatures of the ostrich tribe are 

 usually called, derive their name from the fact that they have a " ratite" or 

 " raft "-like breast-bone. On the latter there is no keel, to which a pectoral 

 muscle may be attached for the purposes of flight, and they have now no 

 mechanism by which they can propel their huge bodies through the air like 

 ordinary birds. That ostriches and their allies will ever fly is simply im- 

 possible, as their numbers are being annually decreased, and the necessary 

 ages requisite for them to develop the means of flight as an escape from their 

 enemies will never be allowed to them, as man, with his spreading civilisation 

 and his deadly rifle, gradually encircles the poor birds in their last havens of 

 rest. The probability is, judging from the well-developed wings of the early 

 ArehcEopteryx, that ancient birds could fly, and that the ostriches and moas 

 are the descendants of birds perfectly capable of flight, but which from the 

 lack of natural enemies in ancient times, have gradually lost their power of 

 flying, and ultimately developed into the flightless birds of the present day, 

 wherein safety is secured by their excellent power of running, or by their 

 nocturnal habits, where concealment and swiftness of foot play the most 

 important part in their preservation. 



The Struthious or Ratite Birds (Sub-class Jiatitce) may, therefore, be divided 

 into six Orders, viz. the Rheas (Rheiformes), the Ostriches (Struthioniformes), 



the Emus and Cas- 

 sowaries {Casuarii- Sub-class 

 formen), the extinct Balitm. 



Moas {Dinornithi- 

 formes and ^pyornithiformes), and 

 the Apteryges {Apterygiformes). Of 

 these the moas are extinct, but 

 members of the other orders still 

 survive. 



The ostriches maybe distinguished 

 by having only two toes instead of 

 three. The moas had three toes, 

 and, therefore, they belonged to the 

 great group of three-toed Struthious 

 Birds, of which so many have per- 

 ished. Of those that survive, the 

 rheas (Rheiformes) are distinguished 

 by the following characters : the 

 absence of any keel to the breast- 

 bone, no hind-toe, and three toes in 



„. , „ „ „ front. They are to all intents and 



Ftg. 1. — THE Common Rhea ^ • i, ^ n 



(BJiea americana). purposes ostriches, and generally go 



by the name of the "South American 

 Ostrich," as they are entirely confined to the South American Continent. Of 

 the rheas, four species are recognised. One of these may be considered an 

 unknown species as yet, as Rhea nana (Lydekker) has only been character- 

 ised from its egg, which is remarkably small, and on this evidence, which is 

 certainly self-evident, Mr. Lydekker has separated the small Patagonian species 

 as distinct. The common rhea {Rhea americana) is the best-known species, 



