INTRODUCTION. 13 



principal external characters of the mineral kingdom are taken 

 from their specific gravity, as compared with water, hardness, 

 crystallization, when it exists, and cleavage, or the direction 

 of the lamellae, which in many minerals is regulated by the rela- 

 tion of the external surfaces to the primary crystal or form. Of a 

 less constant kind are colour, degree of transparency, fracture, 

 and the streak which many minerals show when scratched. The 

 physical characters are fusibility, solubility, phosphorescence, 

 electricity, magnetism, and refraction. 



Linnaeus in his Systema Natures arranged the Animal King- 

 dom into six classes ; the Vegetable Kingdom into twenty-four ; 

 and the Mineral Kingdom into three. As this arrangement, 

 though now modified and extended in many of its parts, as will 

 be detailed elsewhere, forms the basis of modern classification, 

 and was the first successful attempt at arranging in intelligible 

 order the various objects of Natural History, its principal divi- 

 sions are subjoined. * 



ANIMAL KINGDOM. 



CLASS I. MAMMALIA. CLASS IV. PISCES. 



OIIDER I. Primates, ORDER I. Apodes, 



II. Bruta, II. Jugulares, 



III. Ferae, III. Thoracici, 



IV. Glires, IV. Abdominales, 

 V. Pecora, 



VI. Belluae, CLASS V. INSECTA. 



VII. Cete, ORDER I. Coleoptera, 



II. Hemiptera, 



CLASS II. AVES. III. Lepidoptera, 



ORDER I. Accipitres, IV. Neuroptera, 



II. Pica?, V. Hymenoptcra, 



III. Anseres, VI. Diptera, 



IV. Grallae, VII. Aptera, 

 V. Gallinae, 



VI. Passeres, CLASS VI. VERMES. 



ORDER I. Intestina, 



CLASS III. AMPHIBIA. II. Mollusca, 



ORDER I. Reptilia, III. Testacea, 



II. Serpentes, IV. Lithophyta, 



III. Nantes, V. Zoophyte. 



* Systema Naturae, cd. 12. Holmiae, 1766. 



