ART 



SKULL OF A CYNODONT EXTINCT REPTILE. (Afle ' 



Broom.) 



The Cynodonts do not seem to have been very far from the 

 direct ancestors of Mammals. The arrangement of the teeth 

 as incisors, canines, and molars is very mammal-like. But 

 the lower jaw remains a complex of several bones, whereas in 

 mammals there is but one bone on each side. Some of the 

 bones are named: MX. maxilla; SQ. squamosal; DENT, 

 dentary; ANG. angular; ART. articular. 



Photo: W. S. Berridge. 



ECHIDNA OR SPINY ANT-EATER 



This primitive egg-laying mammal ranges from Australia through the Papuan region. 

 There is a related genus, Prcechidna, in New Guinea. The body is covered with strong 

 spines mingled with hair. There are three massive claws suited for burrowing. The 

 mouth is absolutely toothless; the tongue is worm-like; the food consists mainly of ants and 

 other insects. When the egg is laid, the mother takes it in her mouth and places it in her 

 pouch. The shell is broken by the emerging young one. After a time the mother removes 

 the young one from the pocket and leaves it in a burrow while she hunts at night. But she 

 restores it for feeding purposes. The cerebral hemispheres are well convoluted, and the 

 creature is not stupid. It is imperfectly warm-blooded, and hibernates. 



CETACEANS 



ELEPHANTS 



UNGULATES 



RODENTS 



APES 



MONKEYS 

 LEMURS 



LAND CARNIVORES 



AQUATIC CARNIVORES 



INSECTIVORES 



BATS 



SIRENIA 



EDENTATA 



MARSUPIALS 



MONOTREMES 



GROUPING OF THE ORDERS OK LIVING MAMMAL^ 



At the bottom of the scale are the primitive, egg-laying Monotremes, represented by the Duckmole and the Spiny Ant-eater. Above 

 them are the pouched Marsupials, of which the Kangaroo is a type. The remaining Orders fall within the group of Placentals, in which 

 there is an intimate connection between mother and unborn young. Of these, the Edentates (e.g. the Sloth) and the Siremans or 

 "Sea-Cows" may be ranked as archaic forms. Higher up we have the Insectivores (e.g. the Hedgehog); the aquatic Carnivores (e.g. 

 Seals) and the terrestrial Carnivores (e.g. Lion) ; the Rodents (e.g. the Rat) ; the Ungulates or hoofed quadrupeds, and the Elephants; 

 and, marking extremes of mammalian life, the winged Bats and the open-sea Cetaceans or Whales. Finally, there is the great Monkey 

 Stock, including the old-fashioned Lemurs, the true Monkeys, and, highest of all, the Anthropoid Apes. 



