68 



mouth, and thus forming a vacuum. Proper 

 glands also, called salivary, for furnishing a lu- 

 bricating fluid, are found in some of these, as 

 the snail and cuttle, the latter of which has two 

 distinct pairs, but they are not met with in the 

 leech, for an obvious reason. With respect to 

 the tongue, in the greater number of the lower 

 tribes of animals, its place is supplied by palpi, or 

 tentacula, placed around their mouth ; but some, 

 as the snail and the wared whelk, have this or- 

 gan very distinct the first on the floor of its 

 mouth, and the second within its proboscis and 

 in both it is beset with prickles or hooks, appa- 

 rently for retaining the food ; the cuttle also has 

 a tongue of a cartilaginous consistence, and with 

 very little motion. A kind of horny upper jaw, 

 likewise, with several teeth, is met with in the 

 snail, while, in the cuttle, the place of both seems 

 to be supplied by the horny beak already spoken 

 of. The most perfectly formed jaw met with in 

 this tribe of animals, is that of the sea-urchin, in 

 which it constitutes a strong, bony frame-work, 

 commonly known by the name of Aristotle's Lan- 

 tern, surrounding the mouth, and consisting of 

 five pieces, each containing a tooth, which is 

 moved by muscles. Some of this tribe of ani- 

 mals have distinct teeth, without any proper 

 jaws, as the star-fish and sea-anemone, in which 

 they beset the orifice of the mouth, and the sea- 

 mouse, where they are placed on the proboscis. 



Of the apterous insects, the cray-fish has a 



