CHAPTER XXII 

 CLASS III. REPTILIA (LIZARDS, CROCODILES, TORTOISES, SNAKES) 



LABORATORY WORK 



411. Specimens of reptiles are scarcely abundant enough to 

 serve as satisfactory laboratory types for elementary classes, 

 but instructive comparisons may be made by single students or 

 by groups of students. These results should be reported to the 

 class. 



Prepare three parallel columns, one for the lizard, one for 

 the snake, and one for the turtle. Select a specimen of each 

 and compare them with regard to their haunts; habits; food; 

 general form of body; appendages, number, position, joints, 

 digits; covering; manner of locomotion. 



412. Special Topics for Investigation in the Laboratory and Field. 



1. Are reptiles warm or cold blooded? Your evidences? 



2. What are the differences between the scales of snakes and of fishes? 



3. In what various ways is the tail of reptiles used as an organ? How is the 

 tail to be distinguished from the rest of the body ? 



4. What special senses do reptiles possess? What are your evidences? What 

 peculiarities have the organs of sense? 



5. What peculiarities do the internal organs of the snake have which seem to 

 be correlated with the slender, elongate form of the animal ? 



6. What species of snakes, turtles, and lizards are found in your locality? 

 Report on the special habits of each species in so far as you can determine them 

 by observation. Supplement by reference to authorities. 



DESCRIPTIVE TEXT 



413. TheReptilia differ from the vertebrates we have hith- 

 erto studied in the fact that at no period of life do they possess 

 gills. They agree with the lower forms in being cold-blooded 

 and in the incomplete separation of the heart into right and left 

 compartments (except in the crocodiles) . They are, in addition 

 to their air-breathing habit, similar to the birds and mammals 

 in possessing the protective embryonic membranes known as 



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