304 ESSAY ON CLASSIFICATION. 



His arrangement of the animal kingdom is presented 

 in the following diagram, compiled from the twelfth edi- 

 tion, published in 1766. 



CLASSIFICATION OF LINNAEUS. 



CL. 1 . MAMMALIA. Ord. Primates, Bruta, Fera:, Glires, Pecora, Belluae, 



Cete. 



CL. 2. AVES. Ord. Accipitres, Picas, Anseres, Grallas, Gallinse, Passeres. 

 CL. 3. AMPHIBIA. Ord. Reptiles, Serpentes, Nantes. 

 CL. 4. PISCES. Ord. Apodes, Jugulares, Thoracici, Abdomiuales. 

 CL. 5. INSECTA. Ord. Coleoptera, Hemiptera, Lepidoptera, Neuroptera, 



Hymenoptera, Diptera, Aptera. 

 CL. 6. VERMES. Ord. Intestina, Mollusca, Testacea, Lithophyta, Zoo- 



phyta. 



Iii the earlier editions, up to the tenth, the class of 

 Mammalia was called Quadrupedia, and did not contain 

 the Cetaceans, which were still included among the Fishes. 

 There seems never to have existed any discrepancy among 

 naturalists respecting the natural limits of the class of 

 Birds, since it was first characterized by Linnseus, in a 

 manner which excluded the Bats and referred them to 

 the class of Mammalia. In the early editions of the 

 " Systeina Naturae," the class of Eeptiles embraces the 

 same animals as in the systems of the most recent inves- 

 tigators; but since the tenth edition, it has been encum- 

 bered with the addition of the cartilaginous and semi- 

 cartilaginous Fishes, a retrograde movement suggested by 

 some inaccurate observations of Dr. Garden. The class 

 of Fishes is very well limited in the early editions of the 

 Systema, with the exception of the admission of the Ceta- 

 ceans (Plagiuri), which were correctly referred to the 



