340 Animal Biology 



Examples: Turtle (Fig, 152) , snakes (Fig. 152) , lizards (Fig. 151) , crocodiles, 

 chameleons (Fig. 153), and horned "toads" (Fig. 151). 



Class 6 — Aves (a'vez) (L. avis, bird). — Feathers are distinctive of birds. 

 Paired lungs are found in the adult. They are warm blooded with a more or less 

 constant temperature which is usually 10° C. higher than mammals. The fore- 

 limbs are wings which are small in the ostrich and auk. All birds are terrestrial, 

 although some may be associated with water. The heart is four chambered (2 

 auricles and 2 ventricles). There are 14,000 species of birds. 



Examples: Wrens, owls, sparrows, pigeons (Fig. 155), chickens, robins, eagles, 

 turkeys, ducks, terns, gulls, hawks, coots, penguins, and ostrich (Fig. 154). 



Optic Nerve 

 Cerebrum 

 Olfactory Lobe 



Poeterior Nostril 

 Tongue 



» . .. Pulmonary Artery 



-Medulla i p„i„ ' v • 



rulmonary Vein 



Dorsal Aorta 



Glandular StomacL. 



Spermary 



Spleen 



Oil Gland 



Second Digi 

 Third Digi 



•Aperture Of Ureter 

 Aperture Of 

 ^ClMca Sperm Duct 



Duodenum 

 Pancreas 



Fig. 155. — Diagram of the internal structures of a bird of the class Aves. (From 

 Metcalf: Economic Zoology, published by Lea & Febiger. ) 



Class 7 — Mammalia (ma -ma' li a) (L. mamma, breast). — The young mam- 

 mals are suckled by mammary glands (few exceptions). They have paired lungs 

 in the adults. They are warm blooded with a temperature around 37° C. regard- 

 less of surroundings. They possess hair (wool in some types) at certain stages. 

 They heart is four chambered (2 auricles and 2 ventricles). The cranium (brain 

 case) articulates with the vertebral column by means of two occipital condyles. 

 There is a well-developed, usually conv^oluted brain. A muscular diaphragm 

 separates the thorax and abdomen. A tubelike placenta attaches the unborn 

 young to the mother. There are 4,000 species of mammals. 



Examples: Man (Figs. 228 to 256), cat, bat, whale, seal, monkey, kangaroo, 

 elephant, dog, bear, antelope, and prairie dog (Fig. 156). 



