676 - Heredify and Evolution 



Table 32-2— Some Principal Orders of the Eutheria (Placental Mammals)— Continued 



Order 



Common Kinds 



Distinguishing Features 



Edentata 



Armadillos, scaly 

 anteaters, sloths 



Teeth absent or almost absent, that is, reduced to 

 enamelless vestiges of the molars; often with 

 elongate protrusible tongue (anteaters) or long 

 curved claws (sloths). 



Carnivora 



Lions, panthers, cats, dogs, 

 foxes, wolves, minks, 

 weasels, skunks, seals, wal- 

 ruses, etc. 



Small to fairly large flesh-eating mammals with 

 small incisors, large fanglike canines, and sharp 

 molars; legs highly mobile; usually with five 

 clawed toes. 



Ungulata 



Group 1. Cattle, sheep, 

 pigs, deer, giraffes, etc. 



Group 2. Horses, zebras, 

 tapirs, rhinoceroses, etc. 



Fairly large hoofed mammals of herbivorous 

 habit; incisors and molars well developed; often 

 fast running, by virtue of elongation of one or 

 more of the toes; in Group 1 (Artiodactyla), the 

 toes are of even number (2-4); in Group 2 (Peris- 

 sodactyla), the toes are of odd number (1-3). 



Proboscidea 



Elephants 



Generally massive mammals with nose and upper 

 lip modified greatly, forming a long, flexible, 

 muscular proboscis, or trunk; skin thick (pachv- 

 dermatous), loose, and sparsly provided with 

 hair; two of upper incisors elongated into tusks; 

 heavy molars with deeply ridged grinding sur- 

 face; the gestation period lasts about 20 months; 

 young weigh about 20 pounds at birth; maximum 

 recorded individual age, about 50 years. 



Cetac 



Whales, dolphins, and 

 porpoises 



Marine mammals sometimes of great size; fore- 

 limbs finlike swimming organs, hindlimbs ab- 

 sent or reduced to vestigial internal remnants; 

 body streamlined, with an extra thick thermal 

 insulation of fatty t-issue (blubber); include the 

 largest known animal, the sulfur-bottomed whale, 

 which reaches a length exceeding 100 feet and a 

 weight exceeding 150 tons. 



Primates 



Lemurs, monkeys, apes, 

 and man 



Terrestrial mammals, frequently of arboreal 

 habit; limbs elongate; forelimbs with well-devel- 

 oped five-digited hands, the innermost digit being 

 apposable for grasping and climbing; nails flat or 

 cupped; brain and eyes highly developed; eves 

 directed forward; usually producing just one off- 

 spring with each gestation. 



