CHAI.T VIII. 1,000 LITTORINA LITTOREA. PLYMOUTH, MASS. 



20-2 1 mm. 



18-19 mm. 



16-17 mm. 



-15 mm. 



So 81 82 83 84 85 S6 87 S3 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 



