INTRODUCTION. 



The University of Wisconsin requires that each student shall, 

 before graduation, write a thesis on some subject selected either 

 by himself or the professor under whom the work is to be done. 



The subjects of the following four papers were suggested to 

 the students, named below, of the class of 1898. The results 

 of their work were so satisfactory that I have quite largely in- 

 corporated them in the present Bulletin. 



The description of the vascular system of Necturus macu- 

 latus I hope will be of assistance to those who use the animals 

 in their laboratories. Eor several years I have used them in my 

 course in vertebrate anatomy, and feeling the need of some 

 detailed description of the blood-vessels, I kept notes on each 

 animal used. The results, as embodied in the present paper, 

 represent the dissection of over 200 animals and cover four 

 years' work. 



Those who have used Necturus in laboratory courses know 

 how variable they are. The text and diagrams represent the 

 most constant type. I regret that I have not been able to con- 

 sult what is practically the only work on Necturus that is known 

 to me, ''Ontleed en dierkundige bydragen tot de Kenuis van 

 Menobranchus, den Proteus der Meeren van !N'oord-Amerika." 

 J. van der Hoeven. Leiden, 1867. 



I should be very glad to receive any corrections which other 

 workers find desirable on comparison with their own notes; also 

 suggestions on the nomenclature, which I realize is faulty in 

 some places. 



