S6 MAKVELS OF POND-LIFE. 



ever produced by Echinoderms, and bad tbeir de- 

 A'elopnieut cbecked, but tbat they I'esernble theui in 

 organization, and illustrate a general law, observable 

 in animated beings, namely, that the lower creatures 

 are like the imperfect stages of higher animals, and 

 that all thiugs are formed according to general 

 principles, and exhibit a uniformity of plan. 



Mr. Gosse adopts a different view, and while 

 admitting a connection between the Rotifers and the 

 worms, adduces important reasons for associating 

 them with tlie insects. 



Leaving zoologists to settle their position, we n)ay 

 remark that tlie Rotifers form a very numerous 

 family, presenting vei-y great diversities of structure, 

 some of the most interesting of which we shall meet 

 with in the course of our rambles; but they all 

 possess a gizzard, which, though differing in com- 

 plexity, is throughout formed upon the same principle, 

 and that we must now explain. 



We have called the masticatory appamtus of the 

 Rotifers a gizzard; but Mr. Gosse, who has done 

 most to elucidate its structure, contends that it is 

 a mouth; and in some species it is frequently pro- 

 truded, and used like the mouths of higher animals. 

 Taking one of the most typical forms of this organ, 

 and drawing our illustrations from Mr. Gosse's ad- 

 mirable paper in the ''Transactions of the Royal 

 Society," we may describe it, when completely de- 



