ARISTOTLE. 69 



which are destitute of red blood. Of these, he says 

 there are several genera : the mollusca, such as the 

 cuttlefish, which is externally soft with an internal 

 firm part ; the Crustacea, internally soft and covered 

 with a firm integument, such as the crab ; the testa- 

 cea, internally soft and externally hard and solid, as 

 the limpet and oyster. The insects form the fourth 

 genus; and are distinguished by their being external- 

 ly and internally formed of a hardish or cartilaginous 

 substance, and divided into segments ; some of them 

 having wings, as the wasp ; while others have none, 

 as the centipede. He then gives a pretty full ac- 

 count of the cuttlefish and nautilus, treats of the 

 crustaceous animals generally, and enters into de- 

 tails respecting the other two classes. After this he 

 enumerates the organs of sensation, stating that man, 

 and all the red-blooded and viviparous animals, 

 possess five senses, although in the mole vision is 

 deficient. He describes correctly the eye of that crea- 

 ture, showing that it is covered by a thickish skin, 

 but presents a conformation similar to that of other 

 animals, and is furnished with a nerve from the 

 brain. He shows that although fishes have no visi- 

 ble organs of smelling or hearing, they yet possess 

 both senses, and, in treating of this subject, states 

 many interesting facts relative to the mode em- 

 ployed in catching dolphins. He also shows that 

 insects have the faculty of hearing and smelling. 

 The testacea, he says, besides feeling, which is com- 

 mon to all animals, have smell and taste ; but he 

 also asserts that some of them, the solen and pecten, 

 are capable of seeing, and others of hearing. 



All viviparous quadrupeds not only sleep, but also 

 dream ; but whether the oviparous dream is uncer- 



