CHART XIII. 1,000 LITTORINA LITTORF.A. \VARRKX RIVF.R, R.I 



iS-igmnv. 



16-17 mm. 



-15111111. 



So Si 82 83 84 85 S6 S 7 88 S y 9 9' 9' 93 94 95 96 97 98 99 i .o, .02 103 .04 105 .06 



