DAVENPORT, — EVOLUTION OF PECTEN. 



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JO 



E. IS. 



FAY CLASSES |4 



IS 



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Figure 1. 



Polygons of percentage frequencies of rays. 



Eddystone. 



Irish Sea. 



Firth of Forth. 



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The centroid verticals are drawn at E., I. S., and F. F., respectively. 



