DAVENPORT. 



EVOLUTION OF PECTEN. 



157 



DIX F. 



Diameter and Dorso-ventral Diameter. 

 Lower Valve. 



M = 87.594 + .325 ; a - 10.87 ± .231. 



88 



89 90 91 92 



93 94 95 



97 98 99 



100 



101 



102 



103 104 105 



106 



107 



108 



110 111 



112 115 



1 

 3 



5 



4 



2 



7 



4 



5 



7 



10 



11 



10 



10 



20 



15 



16 



19 



26 



27 



24 



31 



26 



20 



26 



28 



29 



29 



33 



16 



19 



7 



6 



3 



5 



2 



2 



1^508 



20 2419 2019 1513 19 1210,13 20 19 7 11 6763432213 



