150 CYCLOBRANCHIATA.—PATELLADA. 
its base. The mouth is fleshy, and contains a long 
slender tongue, armed with spinous teeth, for the 
rasping down of the sea-weeds, of which the food 
of these animals consists. This organ in the 
common Limpet is described as a narrow ribbon- 
like-body, fully three inches long, of nearly equal 
breadth throughout, except at the tip, where it is 
soft and somewhat dilated. The width of this 
singular appendage is not more than one-twelfth of 
an inch; but the surface is armed through its whole 
length, with three parallel rows of spinous teeth, 
pointing backwards. The teeth of the middle row 
are cut into four points, but those of the external 
rows, which are not exactly opposite to, or con- 
tinuous with, those of the middle series, but alter- 
nate with them, are cut into two points only. 
“The first time,” says Mr. Patterson, ‘we 
TONGUE OF LIMPET. 
(The upper figure represents a portion of the surface magnified). 
chanced to see this, we mistook it for some strange 
species of worm; but on examining several Lim- 
pets, the supposed worm was seen in all; and 
great was our astonishment when we discovered 
that we had, in every case, been looking at the 
