AVES 299 



The lungs are connected with an extensive system of air spaces 

 which penetrate far into other parts of the body, even penetra- 

 ting the bones and replacing the marrow. The vocal cords 

 are located at the junction of the bronchi in an organ, the syrinx, 

 which takes the place of the larynx. The right ovary is want- 

 ing and the corresponding oviduct is rudimentary. The eggs 

 are fertihzed in the upper part of the oviduct and are then 

 surrounded by layers of albumen, membraneous shell and cal- 

 careous shell in succession, as they pass down the oviduct. 



648. The eyes and ears are highly developed. There are two 

 eyelids and a nictitating membrane. The ear is without a 

 concha. The brain shows a considerable advance over that of 

 Reptiles, especially with regard to the development of cerebrum, 

 optic lobes and cerebellum. 



649. In many points Birds differ radically from Mammals 

 and at the same time show a strong resemblance to Reptiles. 



650. In a comparatively small group of birds the wings are not used 

 and are consequently rudimentary. These are the running birds or 

 Ratitae — ostrich, emeu and cassowary, the almost extinct apteryx of New 

 Zealand and the recently extinct moa of New Zealand. With the disuse 

 of the wing the muscles have degenerated and with them the keel of the 

 breast bone, their point of attachment. Other birds are called Carinatas 

 because of the keel of the breast bone. They are divided into seventeen 

 orders as indicated in the following synopsis. 



Ratitae. 



1. StruthiomorphcB. Ostrich, rhea, cassowary. 



2. Dinornithes. The recently extinct gigantic Dinornis. 



3. Aepyornithes. The recently extinct .^pyornis. 



4. Apteryges. The Kiwi Kiwis of Australia and New Zealand. 

 Carinatae. 



5. Tinamiformes. South American fowl-like birds. 



6. Gallinacei. Pheasants, turkey, fowl, quail. 



7. ColumhcB. Pigeons, doves. The extinct dodo. 



8. Lari. Gulls. 



9. Grallce. Rails, cranes. 



10. Lamelliroslres. Geese, ducks, flamingo. 



11. CiconicB. Ibis, storks, herons. 



