I certify that I have read this study and that in my opinion it conforms to 

 acceptable standards of scholarly presentation and is fully adequate, in scope and 

 quality, as a dissertation for the degree of Doctor of Philosophy. 



Ljl $ q;iAr^ 



Carter R. Gilber fl, Chair 

 Professor of Zoology 



. -4*.-;^ 



I certify that I have read this study and that in my opinion it conforms to 

 acceptable standards of scholarly presentation and is fully adequate, in scope and 

 quality, as a dissertation for the degree of Doctor of Philosophy. •" .» 



gnK.-. 



David H. Evans 

 Professor of Zoology 



I certify that I have read this study and that in my opinion it conforms to 

 acceptable standards of scholarly presentation and is fully adequate, in scope and 

 quality, as a dissertation for the degree of Doctor of Philosophy. 



Frank G. Nordlie 

 Professor of Zoology 



t;^ 



I certify that I have read this study and that in my opinion it conforms to 

 acceptable standards of scholarly presentation and is fully adequate, in scope and 

 quality, as a dissertation for the degree of Doctor of Philosophy. 



Reiskind 

 Associate Professor of Zoology 



