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PROCEEDINGS OF THE NATIONAL MUSEUM 



China, and the several American genera of Pleurocerinae are among 

 this type. 



A completed study of the various reproductive modifications in 

 this family on a world-wide basis should reveal a very interesting 

 evolutionary pattern and should aid in solving many of the present 

 phylogenetic problems in this group. 



\ 



SOUTHERN 



GUAM 



Figure 40. — Map of southern Guam Island, showing collecting localities and relative mean 

 shell-size of colonies (see p. 103 for explanation). 



