284 MICHIGAN SURVEY, 1908. 



Distribution on Isle Royale: Station I, Sub. 1, Lake and Bay 

 Beaches, Numbers 19, 32, 50 ; I, 5, Jack Pine Eidges, Nos. 19 A, 23, 33, 

 81, 187; I, 7, Light-house Clearing, Nos. 34, 42; II, 1, Eansom Clear- 

 ing, No. 150; II, 2, Tamarack Swamp, No. 113; II, 3, Eock Ridge 

 Clearing, Nos. 51, 145; III, 4, Trail to Sumner Lake, Nos. 88, 93, 138, 

 174; III, 5, Sumner Lake, No. 120; III, 6, Southwest Coves, Eock 

 Harbor, No. 91; IV, 5, Neutson's Eesort, No. 121; IV, 8, Trail to 

 Greenstone Eange, No. 128; V, 2, Heath Zone and Beach, Nos. 101 A, 

 107 A ; V, 3, Eock Clearing at Camp, No. 233 ; VIII, '04, Upper End of 

 Siskowit Bay, No. 232. 



A "dead" shell was foujid in driftwood cast upon the beach at the 

 head of Tonkin Bay (No. 19) and (No. 32) in a small creek at the 

 head of Conglomerate Bay. The animal was dead but the body was 

 still within the shell. In both of these numbers the shells were be- 

 yond their normal habitat. 



Live examples (No. 50) were seldom seen but the abundance of the 

 dead ones upon the rock ridges and open Cladonioi clearings make it 

 apparent that they are abundant here. Numbers, 23, 33, 81, 187, 51, 

 145, 88, 93, 138, 174, 128, 101 A, 107 A, 232 and 233 were all taken from 

 that association. Thence they wander in small numbers to the moister 

 places, such as the lighthouse clearing (Nos. 34 and 42), Eansom 

 Clearing (No. 150), or even in the tamarack swamps (No. 113). 



Although not found at all in 1904, this species was collected in 

 1905 in considerable numbers, which show a wide variation both in 

 size and in the thickness of the shells. The 124 mature specimens col- 

 lected varied in height from 14 to 21.5 mm., and in width from 21.75 to 

 30.75 mm. The average being 17 by 25.86 mm. The accompanying dia- 

 grams, 61-62, show the variation in height and greater diameter. 



A series of 42 from all parts of the Upper Peninsula vary in height 

 from 14 to 20 mm., and in width from 22, 75 to 30 mm., with an average 

 of 17.20 by 26.28 mm. While a series of 183 from all parts of the Lower 

 Peninsula vary in height from 12 to 24.25 mm., and in width from 18.75 

 to 34.25 mm., with an average of 18.10 by 27.11 mm. 



It would appear from these series that the average Isle Eoyale shell 

 is slightly smaller than the average specimen from the Upper Peninsula, 

 and considerably smaller than the average Lower Peninsula example. 

 The range of variation in the Isle Eoyale series is somewhat gi-eater than 

 in the Upper Peninsula series, but much less than in that from the 

 Lower Peninsula. 



2. Acanthinula harpa (Say). 



Eange: "Northwestern Scandinavia, Northeastern America, British 

 America near Hudson Bay, Southeastern Alaska and the easternmost 

 margin of Siberia." (Dall.) 



Michigan: Petoskey and Charlevoix in the Lower Peninsula, and 

 Ontonagon County and Isle Eoyale in the Upper. 



Isle Eoyale: I, 5, Jack Pine Eidges, No. 19 A; II, 1, Eansom Clear- 

 ing, No. 150 ; V, 2, Heath Zone and Beach near Siskowit Bar, Nos. 118 

 A, 129 A, 130 A ; V, 4, Trail through Balsam-Birch Forest, No. 236. 



Numbgr 150 was collected under logs resting on the ground in an 

 open clearing near the lake; No. 236 was in leaf mold in the dense 



