50 



NATURAL HISTORY. 



[Lesson IX. 



rows, like the teeth of a comb, are arranged 

 in small rounded tufts ; the body is coveied 

 with hard plates instead of scales ; the jaws 

 are united, except at the very end, so thrt 

 they appear to have a tubular snout or 

 nose, especially in the sea-horse ; and the 

 male is provided with a pouch, in which 

 the female deposits the spawn, where the 

 young are hatched, and retreat when 

 alarmed. 



119. T. What is the sixth order of the 

 Bony Fishes called? 



P. PLECTOGNATHI, or fishes with sol- 

 dered jaws; so named because the bones 

 of the jaw are immovable. The gills and 

 gill-covers have a covering of thick skin. 



120. T. What is meant by CHON- 



DROPTERYGII ? 



P. Fishes with cartilaginous, instead 

 of bony skeletons. 



121. T. What is the first order of this 

 division called? 



P. CHONDROPTERYGII BRANCHIIS LI- 

 BERIS, or fishes with free gills, such as 

 sturgeons. 



1 22. T. What is the name of the second 

 order ? 



P. ClIONDROPTERYGII BRANCHIIS 



FIXIS, or fishes with fixed gills. These 

 fish have the edges of the gills fixed, instead 

 of being free at the edges, and the water 

 enters through a number of small holes on 

 each side of the head, as in the shark tribe. 



GENERAL QUESTIONS ON LESSON VIII. 



1. How are fishes divided ? 



2. What is the most important object to 

 attend to, and guide us in the classification 

 of fishes ? 



3. How are the young of fish and the 

 species reproduced ? 



4. What do you mean by spinous rays ? 



5. What is the ray of a fin ? 



6. How many orders of Bony Fishes are 

 there? Name them. 



7. Explain the meaning of the various 

 terms applied to each order ? 



8. Give some examples of each order ? 



9. How many orders of Cartilaginous 

 fishes are there? 



10. Name the orders, and their pecu- 

 liarities ? 



LESSON IX. 



WE have now to consider the second great division of the Animal Kingdom the 

 AMMALIA MOLLUSCA, or soft-bodied animals. These animals present many pecu- 

 liarities, being without an articulated skeleton, or back-bone, and without brain or 

 spinal marrow. Their blood is of a bluish tinge, or white ; and their muscles are 

 attached to the integuments instead of to bones. Cuvier says, " that their organs of 

 motion and of the senses have not the same uniformity in number and position as in 

 the vertebrated animals; and the variety is still more striking with the viscera, par- 

 ticularly in relation to the position of the heart and respiratory organs, and even in the 

 structure and nature of the latter ; for some mollusca breathe the free air, and others 

 the fresh or salt water." Some of the molluscous animals have naked bodies, while 

 others are protected by shells. Cuvier divided the molluscous animals into six classes, 

 which we have now to examine. 



123. T. What Is 

 molluscous animals? 



P. The CEPHALOPODES, 



footed animals. 



QUESTIONS, 

 the first class of 

 or head- 



124. T. Why are they called thus ? 



P. Because the animals in this class 

 propel themselves by means of appendages 

 connected with the head. 



125. T. Name some examples of this 

 class of animals. 



