i.j THE COMMON FROG. 7 



us that all these creatures, however different in other 

 respects, all belong to the same ringed type, i.e., that 

 they are all members of the same sub-kingdom 

 Anmilosa^ which contains all such animals, all insects, 

 together with spiders, earthworms, and leeches. 



Another great sub-kingdom called Molhisca con- 

 tains all snails, slugs, cuttle-fishes, and creatures of 

 the oyster and scallop class. Such animals have not 

 the body composed of a series of similar segments, 

 but are united by characters less obvious indeed, but 

 as distinctive. 



A third sub-kingdom called Molhiscoida is made 

 up of the sea-squirts, or Ascidians (sometimes called 

 Tunicates), and lamp-shells, together with minute 

 animals living in water in compound aggregations, 

 like the Flustra (or Sea-mat) so common on our 

 coasts, the surface of which is pitted with small de- 

 pressions, in each of which a mJnute animal had in 

 life its abode — as doves in a dove-cot, if we imagine 

 each dove fastened in its cell by natural growth. 



A fourth sub-kingdom, Anmtloida, is composed of 

 such animals as star-fishes and sea-urchins, toofether 

 with internal parasites (tape-worms, &c.) and their 

 allies. 



The fifth sub-kingdom is named Ccelenterata, and 

 contains all sea-anem.ones, jelly-fishes, Portuguese 

 men-of-war, polyps, and coral animals — these last 

 being the little creatures which have formed the 

 atolls (or coral islands) of southern seas, and the vast 

 reefs which stretched for so many hundred miles on 

 the earth's surface. 



The sixth sub-kingdom, Protozoa, comprises the 



