42 



NATURAL HISTORY. 



[Lesson V. 



P. It has been found necessary to sepa- 

 rate the quadrupeds into two district divi- 

 sions, the warm-blooded and the cold-blooded 

 animals. The former maintain a constant 

 elevated temperature, or nearly so ; are 

 covered with hair, or something resembling 

 it ; bring forth their young alive, or are 

 viviparous, and nourish them by suckling. 

 The latter never have a uniform tempera- 

 ture, but one varying with the atmosphere, 

 and seldom rising above it ; are covered 

 with scales ; and are oviparous, or produce 

 their young from eggs. 



56. T. How do birds differ from mam- 

 malia ? 



P. The class AVES, or birds, are de- 

 cidedly oviparous constructed for propul- 

 sion in the air. The form of the body, the 

 hollow bones, the light feathers, all demon- 

 strate how fitted they are for the element 

 they chiefly occupy. Can we say that they 

 are devoid of some amount of intelligence ? 

 They are superior to reptiles in their orga- 

 nization, and therefore occupy the second 

 class ; and differ from mammalia chiefly 

 in not suckling their young. 



57. T. Why should Reptiles be placed 

 in the third class ? 



P. Because they are intermediate be- 

 tween birds and fishes in their organization. 



58. T. Why are fishes placed in the 

 fourth class? 



P. Because they inhabit the water, are 

 oviparous, not so highly organized as the 

 other classes, and possess distinctive cha- 

 racteristics. 



[The pupil should state the peculiarities of each ; 

 tli us, ii>iies respire the element they inhabit, 

 by nieaus of branchiae or gills; the heart has 



only two cavities, one of which receives the 

 blood from the system, and the oilier propels 

 it through the gills, &u.j 



59. T. Do not some reptiles and fishes 

 produce their young alive ? 



P. Yes. 



[The pupil should name the species that do so.] 



60. T. Are there not peculiarities in 

 Mammalia, that render it almost necessary 

 to separate them into another class ? 



P. Yes, there are peculiarities, but not 

 sufficient to warrant us to form another 

 class. Thus, one tribe possesses the power 

 of rising into the air, like birds, and another 

 lives in the water, like fishes, but then they 

 agree in all the essential characteristics of 

 the other mammalia, while they differ 

 materially from the classes with which they 

 appear connected. 



GENERAL QUESTIONS ON LESSON IV. 



1. What is the best way to study Natural 

 History ? 



2. Why are Vertebrata placed first ? 



3. How can you tell where an animal 

 should be classed ? 



4. What is the difference between a 

 monkey, a marmoset, and a lemur ? 



5. How is the sub- kingdom VERTEBRATA 

 naturally divided ? 



6. Enumerate the four classes of vertebrate 

 animals. 



7. Give the reason that Mammalia is 

 ranged before the other three classes, and 

 why each is placed where it is. 



8. What is the difference between warm- 

 blooded and cold-blooded animals ? 



9. Explain the terms Viviparous and 

 Oviparous. 



LESSON V. 



WE have already seen that the Mammalia form the highest group in the animal 

 kingdom, and were placed at the head of this kingdom, as Cuvier remarks, " Not only 

 because this is the class to which we ourselves belong, but also because it is that which 

 enjoys the most numerous faculties, the most delicate sensations, the most varied powers 

 of motion, and in which all the different qualities seem together combined to produce a 

 more perfect degree of intelligence, the one most fertile in resources, most susceptible 

 of perfection, and least the slave of instinct" In classifying animals, the naturalist 

 aims at establishing that system which is most natural, therefore he examines those 

 characters which are easily recognised and understood ; and, on this account, selects the 

 external appearance of each, so that those having the greatest resemblance are associated 



