14 
SECOND BOOK. 
In another we place animals whose bodies are in 
ring-like portions : of these the crabs, lobsters, 
insects, and spiders have legs jointed to the body, 
while the worms are without legs. Then, in the 
other sub-kingdoms there are the sea-anemones, the 
‘jelly-fishes’, the creatures that make the corals and 
sponges, and many others. 
5. “Of these boneless animals I shall not say 
much, and we will, for the present, think no more 
about them. I should like to tell you a little now 
about the great sub-kingdom of Vertebrates, or 
back- boned animals.” 
6. “That is the sub -kingdom to which we 
belong,” said Arthur. 
“Of course,” said Mr. Johnson, “and we are in 
the first class too.” 
7 . “ What do you mean?” asked Arthur. 
“ I mean that amongst the animals that agree in 
having a backbone we find such great differences 
in other ways, that we are able clearly to form them 
into classes. 
8. “ And into the first class, to which we of course 
belong, we put all animals that are fed with their 
mother’s milk when young, and these we call 
Mammals. 
“ I think you could mention some backboned 
animals that are not in this class.” 
“Yes: the birds,” said Arthur. 
9. “ Quite right,” replied Mr. Johnson. “ They 
