lOli MARVELS OF POND-LIFE. 



are soldered together into two siibquadrantic-globular 

 masses, which appear to be miiscidar, but invested 

 with a solid integument. The manuhria (handles) 

 may still be recognised in a vertical aspect as three 

 loops, of which the central one is chiefly developed, 

 and in a vertical aspect as a translncent reniform 

 (kidney-shaped) globe." These descriptions are not 

 easy to understand, not from any want of clearness 

 or precision in the words employed, but from the 

 complicated character of the organ, and its very 

 different appearance under different aspects. To 

 make the matter more intelligible, Mr. Gosse adds, 

 ''the structure and action of an apparatus of this 

 type may be made more clear by a homely illus- 

 tration. Suppose an apple to be divided longitu- 

 dimdly, leaving the stalk attached to one half. 

 Let this now be split again longitudinally so far 

 as the stalk, but not actually separating either 

 portion from it. Draw the two portions slightly 

 apart, and lay them down on their rounded sur- 

 faces. They now represent the quadrantic masses 

 in repose, the stalk being the fulcrum, and the 

 upper surfaces being crossed by the teeth. By the 

 contraction of the muscles, of which they are com- 

 posed, the two segments are made to turn upon 

 their long axis, until the points of the teeth are 

 brought into contact, and the toothed surfaces rise 

 and approach each other. The lower edges do not 



