Plate V 



Variation in Thais lamellosa as suggested by 

 Dr. W. H. Dall (1915, pi. 74.).- 5. var. cymica; 

 6. var. franciscana; 7. lamellosa typical; 8. var. 

 hormica . 



Fossil form of Thais lamellosa from the Pleisto- 

 cene of Washington. From Weaver (1942, pi. 88/ 



