CHART VI. 1,000 LITTORINA I.ITTOKEA. ISEYFRLY, MASS. 



20-21 mm. 



i-nj mm. 



16-17 mm. 



-15 mm. 



80 Si 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 too joi 102 103 104 105 106 



