40 NATURAL HISTORY. [Lessen IV 



They have a complete circulatory system, I p._Y es , by Maclcay, who formed, 

 and particular organs for lesuhaiiou. j another called ACRITA, or acrite animals;' 



4k '7'. What is the last sub-kingdom I hut as we have yet to learn more of the 



peculiarities of each, we must wait until 



named ! 



P. KADI AT A, or radiate animals. They 

 have their organs of sense and motion 

 aiTcinged as rays around a centre. They 

 have- no very distinct nervous system, or 

 particular organs of sense; and in some of 

 them it is is extremely difficult to discover 

 any circulation. The respiratory organs 



we commence Zoology. 



GENERAL QUESTIONS ON LESSON III. 



1. What is the aim of all scientific men 



when studying Natural History 



2. How is ihe Animal Kingdom divided ? 



are generally on the surface of the body. 3. Describe the peculiar characteristics 



4"). T. Have not the radiated animals j of the sub-kingdoms Venebrata, Mollusea, 

 been divided, so as to form another sub- Articulata, and Hadiata. 

 kingdom? 4. Are there only four sub -kingdoms ? 



LESSON IV. 



THE celebrated Baron Cuvier, whose method we shall adopt in this Catechism, observes, 

 that "the habit necessarily acquired in the study of natural history, of mentally classi- 

 fying a great number of ideas, is one of the advantages of this science which is seldom 

 spoken of; but which, when generally introduced into the system of common education, 

 will perhaps become the principal one. It exercises the student in that part of logic 

 which is termed method, as the study of geometry does in that which is called syllogism ; 

 because natural history is the science which requires the most precise method, as 

 geometry is that which demands the most rigorous reasoning. Now, this art of method, 

 when once well acquired, may be applied with great advantage to studies the most foreign 

 to natural history. Every discussion which supposes a classification of facts, every 

 research which requires a distribution of subject, is performed after, the same manner; 

 and he who has cultivated this science merely for amusement is surprised at the facilities 

 it affords for disentangling all sorts of affairs." 



Those who desire to master natural history must adopt a system to facilitate its study, 

 and this is only done by observing and noting the characters and attributes of the vast 

 numbers of objects in organic and inorganic creation. It is absolutely necessary, just 

 as much as it is to arrange the various matters in a house. If you wanted a spoon, and 

 had to look for it amongst a heap of knives, forks, scissors, and other things, you would 

 :iich time, and perhaps after all your labour it might not be there. So it is with 

 1 history; if you wanted to find the description of a kangaroo you would refer to 

 Division I. Vertebrata, Class I. Mammalia, Order IV. Mar.tiifiitita ; and then you would 

 procure the information required; and nothing is more easy, because every animal has 

 some leading feature, which fixes its position in the catalogue of nature, and this is 

 chiefly determined by its organization. 



QUESTIONS. 



46. T. Why did Cuvier place the ver- 

 tebrate animals first? 



P. Because they are more highly or- 

 ganised than the others. 



47. T. Explain how this is. 



P. In the first place, the nervous system 

 is better developed,, consisting of a brain 

 and prolongations ; whereas in the mollus- 



