PREFACE TO PART III 
Volume II contains the Marine Gastropods and is in three parts, of 
which this is the third and last part. 
Many of the plates here used are from the Proceedings and Bulletins of 
the United States National Museum. In some cases species for comparison 
from Lower California and south of there are included on the plates, but 
are not described in the text. 
The United States National Museum had photographs made of some 
of the unfigured species to use in the plates. The American Museum of 
Natural History, New York City, also had photographs made of some of 
the type figures. Many of the figures in Bulletin 112 and in some of the 
Proceedings have been refigured for use in making up the plates. 
The line or lines preceding the description of a shell in the text give 
the reference to the original description and figure. 
Acknowledgments are given in the Preface to Part I. 
I. S. Oldroyd 
June 15, 1927 
[ 605 ] 
[3 
