106 Kansas Academy of Science. 



Pliocene : Eagle Prairie and Danger creek, Humboldt county, 

 California; Santa Rosa; San Fernando (Cooper); San Diego (Ar- 

 nold). 



Miocene : Sunol, Alameda county ; Foxin's, Santa Barbara 

 county, California (Cooper). 



Macoma indentata (Carpenter) (?). Figure 11. 



Arnold's description (in part).'^ Shell rather narrow, suboval, 

 compressed, thin; umbones slightly posterior to center ; anterior 

 end long and evenly rounded ; posterior dorsal line straight ; pos- 

 terior extremity much projected and sharply rounded ; fold promi- 

 nent. 



Dimensions: Length, 14 mm.; alt., 10.5 mm.; umbo to posterior 

 extremity, 8.5 mm.; to anterior extremity, 10 mm. 



This shell is like M. indentata described by Arnold, except it is 

 much smaller. 



Macoma inquinata (Deshayes). Figure 12. 



The only specimen obtained is the broken left valve represented 

 in the figure. 



Shell convex, thin ; umbones subcentral ; anterior end dilated ; 

 posterior end evenly arcuate from umbo and acutely rounded at 

 posterior end. 



Dimensions: Length, 11.5 mm.; alt., 8 mm.; umbo to anterior 

 extremity, 7 mm.; to posterior extremity, 7 mm. 



This shell is also much smaller than M. inqui7iata described by 

 Arnold.io 



Macoma concentrica (Burg.) Figure 13. 



Though much broken, this shell was easily identified by com- 

 paring it with specimens in the university museum at Seattle. It 

 resembles M. nasuta very much, except that its umbones are slightly 

 posterior and the fold on right valve is less prominent. 



Dimensions: Length, 33 mm.; alt., 22 mm.; thickness of right 

 valve, 2.5 mm. ; umbones to anterior extremity, 18 mm. ; to posterior 

 extremity, 15 mm. 



Living: In Florida. 



9. Loc. cit., p. 161. 



10. Loc. cit., p. 162. 



