180 



FIRST BOOK OF ZOOLOGT. 



low, in order to gain an insight into the affinities existing 

 between the various groups composing this great branch of 

 animals. 



metatarsus. 



pTialOTige^. 



Fia. 158. — Bones of the Eight Leg of a TorxG Toap greatly enlarged.— The fenmr 

 is not shown in this drawing ; the tibia and fibula are combined together. 



There are still other large classes of animals forming 

 branches or sub-kingdoms quite distinct from those already 

 studied, and represented by animals which live in the sea, 

 such as the star-fish, sea-urchin, jelly-fish, and sea-anemone, 

 of which no mention will be made in this book. There are 

 also many classes, belonging to branches already touched 

 upon, which have not been alluded to. These will be fully 

 dealt with in the second book, now in preparation. 



