IV PEEFATORY NOTE. 



incomjjlete, owing to the unfortunate sickness of the author^ Professor 

 Allen, which iDrevents the continuation of the Bibliography of the 

 Cetacea and Sirenia in the serial. 



Yolumes lY and Y were issued under the supervision of Dr. Elliott 

 Coues, D". S, A.^ and Yolume YI was- completed by W. H. Holmes. 



F. Y. HATDEIS^, 

 XTnited Mates Geologist. 



