COMPARISONS. 



Divide a page of your note-book by a vertical line. 

 Head one column Dogfish, the other Bony-fish, and in 

 each column write the answers to the following questions, 

 numbering them as they are here: 



(1) What kind of scales occur? 



(2) Where is the mouth? 



(3) What is the shape of the caudal fin? 



(4) Point out all the differences between the gills of 

 the two. 



(5) Where are the nostrils? 



(6) Are the hard parts cartilaginous or bony? 



(7) Is there a spiral valve in the intestine? 



(8) Is there a swim-bladder? 



(9) Is there an operculum? 



After answering these questions read carefully the sec- 

 tions on Elasmobranchs (pp. 322 to 325) and on Teleosts 

 (pp. 326 to 336). 



Prepare another sheet as before with columns for dog- 

 fish and bony-fish and answer the following questions: 



(1) Where does the animal live? 



(2) Is the surface of the body naked or scaled? 



(3) Is there a skeleton to the median fins? 



(4) Is there anything which could be called a hand or 

 foot? Is the skeleton of the paired fins provided with 

 knee, elbow, wrist, etc.? 



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