VERTEBRATES. 19 



tected by shells ? Name from the chart the largest genus of known shells. 

 Is it a bivalve, (of two pieces,) or a univalve, (of one piece?) 



Which is the fourth, last and lowest branch of the Animal Kingdom ? 

 Define Radiate. How are the parts disposed ? Where is the mouth,? From 

 what is the term derived ? Are they aquatic ? What is said of these ani- 

 mals near the bottom of the chart, on the left hand ? Are they less per- 

 fect of their kind than those on the right branch ? Why, then, are they 

 said to be the lowest in the scale of animal life? Which animals are 

 always lowest in organization in the class, division, or order to which they 

 belong ? Which rank next in the ascending scale ? Which rank highest 

 of all ? Which is the lowest order of land animals which nurse their young ? 

 Ans. The. MONOTREMATA and MARSUPIALS. Why are the branches of the 

 orders Marsupialia and Rodentia, (gnawers,) bent and carried around next 

 the marine mammals ? Aus. To show that though having nails, they come 

 next the order Cetacea, (Whales, Dolphins, &c.,) in organization. Which 

 is the lowest or most simply organized class of animals? Mow many 

 orders does it contain? What does proto signify? Is it a well 

 established class ? What is said of it ? What animals are found on the 

 chart among the RADIATES? Which are microscopic? Which fossil? 

 Which used as food ? What is said of Sponge ? Where does Agassiz class 

 it? Are Animalcules, Infusories, and Microscopic or very minute animals 

 common ? Ans. They are dispersed like seed through all nature. Are 

 Animalcules tenacious of life? Ans. It is so difficult to kill them that 

 they can be repeatedly dried and kept for a long time, and will revive 

 or come again to life, as soon as put into water. 



FIRST BRANCH OF ZOOLOGY. 



MAMMALOGY, (Gr. /ua^a, mamma, a breast; Myos, logos, 

 a discourse.) 



L GRAND DIVISION OF VERTEBRATES, (Warm-Blooded Animals,) 



SECTION III. 



VERTEBRATES. 



(Lat. Vertebrata, possessing Vertebra, or joints in the backbone.) 



The first class of the Vertebrates consists of the Mammals, or 

 Mammalia, (Gr. Mamma, a breast.) a term first used by Linnseus 

 and designating all animals which nurse their young. The 

 highest position in the Animal Kingdom is given to this class, 

 composed as it is of beings whose faculties are the most numer- 

 ous, which are most perfect in tbeir structure and capable of the 

 most varied movements, and whose intelligence is most largely 

 developed. A large part of the Mammals are formed for walk- 

 irj ; some can fly in the air, and water is the element in 

 which others live and move. Their skeletons are all constructed 



