PREFACE, ^ ';fi^ 



sect ; and, partly for* this reason, partly because the great 

 persistence of vitality in its various organs after general 

 death of the animal makes it extremely promising for 

 physiological experiment, it was the one for whose 

 dissection I first drew up laboratory directions for the 

 use of my students. Finding them of great value in 

 saving time to teacher and pupil, and also in prevent- 

 ing the waste of material which is apt to occur when a 

 student sits down without specific directions to dissect 

 an animal whose structure is almost entirely unknown 

 to him, I thought they might be of use in other labora- 

 tories. I accordingly asked my friend and former 'pu- 

 pil. Dr. William A. Moale, to assist me in preparing for 

 publication detailed directions for the dissection of a 

 number of vertebrate animals. The present pamphlet 

 will shortly be followed by two others, containing direc- 

 tions for the dissection of a pigeon and a rat, both of 

 which are well on the way toward completion. We in- 

 tend ultimately to include in the series a bony and a 

 cartilaginous fish, a lizard, and one of the large-tailed 

 amphibia which form such a characteristic feature of 

 the American Fauna. 



In the present instalment of our work, Pseudemys rii- 

 gosa^ though far from being the most widely distributed 

 of American Chelonia, is the species selected for de- 

 scription,»mainly because it is sold in the markets here 

 during the winter months, and was, therefore, readily 

 obtainable by us. The fact that in many places this 



