Marvels of Pond-Life. 27 



adduces important reasons for associating them with 

 the insects. 



Leaving zoologists to settle their position, we may 

 remark that the Rotifers form a very numerous family, 

 presenting very 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 complexity, is throughout 

 formed upon the same principle, and that we must now 

 explain. 



We have called the masticatory apparatus 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 protruded, and used 

 like the mouth of higher animals. Taking one of the 

 most typical forms of this organ, and drawing our illus- 

 trations from Mr. Gosse's admirable paper in the 

 "Transactions of the Royal Society/' we may describe 

 it, when completely developed, as consisting of three 

 lobes, having a more or less rounded form. The 

 eminent naturalist we have named calls the whole organ 

 the mastax, and states that it is composed of dense mus- 

 cular fibre. The tube which leads down to it he 

 designates the " buccal (mouth) funnel," and the tube 

 that issues from it, and conveys the food to the digestive 

 sac or stomach, he calls the oesophagus, in conformity 

 with the nomenclature applied to creatures whose 

 mouths are in the usual place. Inside the mouth- 

 gizzard are placed two organs, which work like ham- 

 mers, and which Mr. Gosse therefore names mallei. 

 The hammers work against a sort of anvil, which is 



