24 GENERAL CONCEPTIONS. 



The second class is that of the Marsupials, familiar to us in America through 

 the common opossum. In Australia there are many genera and species of 

 marsupials. 



Annelida 

 Atriozoa 



Tunicata (Ascidia) 

 Cephalochorda 

 Amphioxus 

 Yertebrata 



Anamniota (Anallantoidea) 

 Ichthyopsida 

 Pisces 



Marsipobranchia (lampreys, etc.) 

 Ganoidea (sturgeon, etc.) 

 Teleostea (bony fishes) 

 Elasmobranchia (sharks, skates, etc.) 

 Dipnoi (lung-fishes) 

 Amphibia 



Urodela (newts, salamanders, etc.) 

 Anoura (frogs, toads) 

 Amniota (Allantoidea) 

 Sauropsida 



Reptilia (lizards, crocodiles, snakes, turtles, etc.) 

 Aves 

 Mammalia 



Montotremata (duck-bill, etc.) 

 Marsupialia (opossum, kangaroo, etc.) 

 Placentalia 



Unguiculate series 



Insectivora (moles, etc.) 

 Cheiroptera (bats) 



Rodentra (rats, rabbits, guinea-pigs, etc.) 

 Carnivora (cats, dogs, etc.) 

 Primata (lemurs, monkeys, apes, man) 

 Ungulate series 



Ungulata (horse, sheep, pigs, etc.) 



The third class comprises the majority of well-known mammals, and may 

 be termed the Placentalia, and, for embryologieal purposes, it is convenient to 

 consider the Placentalia as forming two principal subclasses, the animals with 

 claws and the animals witli hoofs, the Unguiculates and the Ungulates. Of the 



