Lesson III.] 



NATURAL HISTORY. 



QUESTIONS. 



30. T. You have said that the Animal 

 Kingdom is divided into several parts ; 

 what is the name of the first sub-kingdom ? 



/'. VKKTEBRATA, or vertebrate animal*, 

 so called because the individuals comprised 

 in this division have a backbone or verte- 

 bral column, composed of several parts, 

 each of which is called a vertebra. 



31. T. Why have these animals a back- 

 bone or spine composed of several parts ? 



P. Because it affords them nmre 

 strength and flexibility, and gives their 

 movements more precision. 



T. Is there no other use for this 

 vertebral column ? 



P. Yes : it protects a bundle of nervous 

 confined within a sheath, which is 

 called the spinal marrow, or medulla 

 tpinalit ; and also supports the skull. 



33. T. What is the use of the skull ? 

 P. To protect the brain, and organs of 



tense connected with it. 



34. T, What is attached to the other 

 end of the spine ? 



P. It is prolonged, and contracted into 

 a tail, the size and length of which usually 

 increases in proportion as the skull de- 

 creases. 



85. T. What other attachments has 

 the spine ? 



It i connected at the sides with a 

 series of peculiar shaped bones, called the 

 ribs, which are again attached in front to 

 a breast-bone. 



36. 7*. -What is the use of the ribs ? 

 P. To enclose and afford prote 

 the organs of respiration, circulate 



is there peculiar in t In- 

 struct urr of vertebrated animals ? 



P. They have an mi, mat skeleton, a 

 ire en- 

 dowed with all ih- / biood, 

 tiellrd through the system by 

 iiUr heart, and separate sexes 

 organs of 1 .;o not exceed two 

 ; 



iily two jaws, placed one ahont or 

 Vbrr the o- ng sideways, 



and usually furnished with teeth. 



largest animals belong to this d 

 and are remarkable for possessing a greater 

 degree of intelligence than any other class 

 of animals. 



38. T. Do all the animals comprised 

 in this class present the Fame peculiarities ? 



P. Yes, there may always be found 

 some analogy, even in the most remote 

 species, of an unifonn plan. 



39. T. You named another sub-king- 

 dom. What is it called? 



P. ARTICULATA, or articulate animals. 



40. T. Why are they called articulate ? 

 P. Because the skeleton is in pieces, 



jointed, or articulated together. 



41. T. In what respect do they differ 

 from the vertebrate animals ? 



P. The skeleton is external, covering 



the whole body; while, in the former, the 



muscular part is external. The nervous 



is not so highly developed, the 



organs of hearing and smell being generally 



deficient. The legs are frequently nume- 



rous, but never less than six. T:. 



always open laterally, and they usually pos- 



:e than one pair; and the blood 



42. T. What is the second sub-kingdom 

 called ? 



P. MOM.USCA, or molluscous animals. 



43. T. What is there peculiar in their 

 organization ? 



/'. I \ have not any skeleton the 



I attached to" the skin. 

 utes a soft contractile env. i 

 which strong plates, called shells, are found 

 in in >(.. .c production .mil posi- 



. lu.-h are analogous to thoM 

 <-era and i 



system, which are composed of several 



i misses connected by nervous 



ts, are contained within thin general 



envelope. The brain is pin 



oetophaftu, or gullet, and i 



principal ronj).. -ting nervous filament. 



:nily only J.M^M-VM . the organs of 



hearing; and Uute and vision are the only 



senses, with this . which this 



class presents ; frequently vision is wanting. 



