452 CHORDATA. 
quadrate has only a single articulation with the skull. The 
Ratite illustrate discontinuous distribution. The ostrich 
(Struthio) is found in Africa and South-Western Asia. It 
has only two toes—a large fourth and a small fifth. The 
American ostrich (ea) has three toes and is found in 
South America. The Cassowary (Casuarius) and Emu 
(Dromeus) are found in the Australian region and the small 
Kiwi (Apzeryx) in New Zealand. On this latter island are 
also found the remains of the recently extinct Moas (Din- 
ornis), huge wingless birds. Others have been found in 
Madagascar. 
an 
Fig. 319.—THE Kiwi (Apteryx) x 
‘A wingless ” bird of New Zealand. The wings are vestigial 
and hidden below the feathers. 
OrvDER II.—Carinate. 
The Carinate comprise the remainder of modern birds. 
Considering the enormous number of species and wide dis- 
tribution, they present remarkably few structural differences 
which are available for classification. In one or two fossils, 
such as the Cretaceous Hesperornis and Lchthyornis, teeth still 
survive. 
They are classified by reference to the arrangement of 
the feathers, the structure of the skull and of the alimentary 
organs. 
