82 RAMBLES OF 



species the teeth are five in number ; but throughout this 

 class of animals the same general principle of construc- 

 tion may be observed. Crabs and their kindred have no 

 brain, because they are not required to reason upon what 

 they observe ; they have a nervous system excellently 

 suited to their mode of life, and its knots or ganglia send 

 out nerves to the organs of sense, digestion, motion, &c. 

 The senses of these beings are very acute, especially their 

 sight, hearing and smell. Most of my readers have heard 

 of crabs' eyes, or have seen these organs in the animal 

 on the end of two little projecting knobs, above and on 

 each side of the mouth ; few of them, however, have seen 

 the crab's ear, yet it is very easily found, and is a little 

 triangular bump placed near the base of the feelers. This 

 bump has a membrane stretched over it, and communi- 

 cates with a small cavity, which is the internal ear. The 

 organ of smell is not so easily demonstrated as that of 

 hearing, though the evidence of their possessing the sense 

 to an acute degree is readily attainable. A German na- 

 turalist inferred, from the fact of the nerve corresponding 

 to the olfactory nerve in man being distributed to the an- 

 tenna?, in insects, that the antennae were the organs of 

 smell in them. Cuvier and others suggest that a similar 

 arrangement may exist in the Crustacea. To satisfy my- 

 self whether it was so or not, I lately dissected a small 

 lobster, and was delighted to find that the first pair of 

 nerves actually went to the antennee, and gave positive 

 support to the opinion mentioned. I state this, not to 



