124 ECHINODERMATA. 



of others in front brings forward the shell ; the hind suckers are again 

 affixed, after which those before relax, and thus the step is taken. 



The suckers are therefore the instruments of progression, wherein 

 they are but feebly aided by the spines, although these may be of some 

 utility, being about an inch long, and, besides any other functions, afford- 

 ing a formidable means of defence. 



The Echinus advances in its course uninterruptedly with wonderful 

 expedition, yet never quitting the water, and sometimes remaining long 

 close under the surface. 



The power of the suckers seems dependent on the presence of the 

 circumambient fluid, a fact of some utility to be known, for on emptying 

 the vessel of sea-water, all the suckers detach themselves successively, 

 and free the specimens, adhering within, without violence. 



Though discoursing familiarly of the interspersion of the numberless 

 organs, all are arranged in the most beautiful and symmetrical order, 

 which, to be duly appreciated, must be beheld not only in the living 

 animal, but in its remains, after life has fled. 



How many examples do not we daily discover of the will of the 

 Great Architect of the Universe, being alone capable of such effects ! 

 What other evidence of nameless power would mankind require than the 

 existence of such marvellous works, to be continually recognised by the 

 exercise of their own personal faculties ? It is not on one object only, 

 but on an endless series that their admiration can be bestowed. They 

 are always renewed, never exhausted, while every subject, in its won- 

 drous structure and use, seems to surpass that which has preceded it. 



Let us contemplate the appearance and employment of the principal 

 organs of the Echinus. Contrary to the ordinary arrangements of nature, 

 the mouth is situated in the under surface, always in ready contact with 

 the plane of position. Here a depression of the shell marks a well 

 guarded orifice as its site, from which projects the acuminated union of 

 five strong teeth, united as a cluster, to form a sharp extremity in one 

 point. The intestines, within, wind up to the vertex, from which the 

 ovaria discharge their contents. 



If a specimen fished up from the sea be cast into a vessel of water, 



