68 Baron Cuvier's Lectures on the Natural Sciences. 



the latter is not attached to its shell. He briefly describes all 

 the parts of these animals, and even speaks of their brain, whicli 

 is a very remarkable circunastance, as the existence of such an 

 organ in the moUusca has only been demonstrated within these 

 few years. 



The subdivisions which he proposes among the white-blooded 

 animals, are still better than his principal divisions. In the 

 class of Insects, for example, it is precisely the same as that of 

 Linnseus. He distinguishes insects according as they have 

 wings, or are destitute of these organs, and forms of those 

 which are winged, three sub-orders, according as their wings 

 are two or four, or are covered with horny plates. After this, 

 he explains what he means by genus .in zoology, and gives, as 

 an example, that of the Solipeda, which consists of the horse, 

 the ass, and the wild mule of Syfia (Hemionus). This is, in 

 fact, a perfectly distinct genus, and one of those which we 

 should at the present day adduce in preference. 



Aristotle, after this introduction, which, as he himself says, 

 is presented as an excitement to the study of natural history, 

 passes to the description of the different parts of animals, taking 

 as a point of departure the human body, which he uses as a 

 term of comparison, and as a basis for his nomenclature. He 

 first treats of the great i-egions, and of all that can be seen at 

 the exterior ; and then passes to the examination of the internal 

 parts. Here his observations are not so correct as before. The 

 great features of the organization, however, are pretty well 

 known to him ; and it would even appear that, with respect to 

 certain points of detail, he knew more than most of his succes- 

 sors. He knew, for example, the Eustachian tube, and speaks 

 of it in the passage in which he refutes Alcmeon, who main- 

 tained, as we have already said, that goats respire by the ears. 

 He commences his description with that of the brain, and says, 

 that that organ occurs in all the red-blooded animals, without 

 exception ; but that among the white-blooded animals, the mol- 

 lusca are the only ones in which it is found. Man, he adds, 

 has of all animals the largest brain. He gives a pretty good 

 description of the two membranes which envelope that organ, 

 and the different nerves which issue from it to be distributed to 

 the eye. His neurological observations go no farther, however ; 



