538 Annals of the Carnegie Museum. 



North Harbor Island. 

 Diam. 23.16, Alt. 14.56 mm., Index 62.87 average of 16 shells. 



Middle Sister Island. 



Dlam. 2zj.os, Alt. 14.66 mm., Index 60.96 average of 129 shells, 

 " 27.00, " 16.50 " " 61.10 largest, 



" 21.50, " 14.00 " " 65.10 smallest, 



" 23.50, " 16.00 " " 68.08 most elevated, 



" 25.50, " 14.00 " " 54.90 most depressed. 



Variation in diam. from 21.5 to 27.0 or 5.5 mm. 

 " alt. " 73. " 16.5 " 3.5 " 



One hundied eighteen shells vary in diam. from 23 to 26 or 3 mm. 



One hundred fourteen " " " alt. " 14 " 16 " 2 " 



Of the above 248 shells, 231 or 93.14 per cent, are from 21 to 25 mm. 

 in diam. and 205, or 82.66 per cent., are under 25 mm. The average 

 diam. is 23.5, alt. 14.54 mm., index 61.86. 



Type-locality Green (formerly Strontian) Island, Lake Erie, Ohio. 

 Types No. 7466 of my collection. Paratypes in collections of Bryant 

 Walker, Detroit, Michigan, and Calvin Goodrich, Toledo, Ohio. 



On Put-in-Bay Island, the profunda are of the large, flatter, main- 

 land form. They are also brighter in color. 



Thirty-eight shells from four localities in Ohio, Illinois, and Ontario 

 were measured, and gave an average of 26.87 X 15. i mm., index 56.10. 

 Shells from farther south are much flatter, as the average of thirty-two 

 shells from five localities in Kentucky, Virginia, and North Carolina 

 is 28.84 X 14.82 mm., index 51.4. The smallest of these thirty-two 

 shells is 25.5 X 13.5 mm. and the largest 33 X 16.5 mm. The most 

 depressed, excluding abnormal shells, had an index of 46.88 and the 

 most elevated 55.77. 



The specimens of profunda from Green Island appear to be losing 

 the bands, as out of one hundred and three examined thirty-seven are 

 banded, thirty-two are unicolorous and thirty-four are albinos. The 

 bands are faint to obsolete and generally split, many of the unicolorous 

 shells are so light that they might be called albinos. The large pro- 

 portion of bandless shells, about 65 per cent., would seem to indicate 

 the formation of a bandless race. On Middle Sister Island the pro- 

 portion of bandless shells is smaller, as out of one hundred and thirty- 

 four shells twenty-nine are of a uniform brown color, four are straw- 

 colored, four are albinos, sixty-seven have a single brown band and 

 thirty have two or more bands, the lower one usually split, and many 



