226 



THE ANIMAL KINGDOM. 



name; they are also called Sea-eggs or Sea-urchins (fig. 11), 

 and are mostly of a conical or spherical shape, divided into 



PIG. 11. SEA-URCHIN (Echinus), WITH AND WITHOUT SPINES. 



five segments covered with minute holes, from which project 

 tentacular serving as organs of locomotion, touch, &c., and the 

 surface of the body is covered with shelly spines of various 

 forms and thicknesses ; the mouth is in the centre, and they 

 feed upon marine productions. The spines, if cut across 

 and ground thin so as to be transparent, show a most com- 



PIG. 12. SPINE OF ECHINUS (A, natural size, u, a section magnified). 



plicated and beautiful structure when under the microscope 

 (fig. 12). 



The Star-fishes are inhabitants of the sea, and have 

 generally five arms covered beneath with tentaculae having 

 small suckers at the point, it is by means of these that they 



