98 MICHIGAN SURVEY, 1905. 



plants in Washington river, II, and attached to the rocks about the shore 

 of Washington Harbor, X. 



27. Aplexa hypnorum (L.). II. Found onh^ among the fallen ahler 

 leaves on a wet flat on Washington river. 



28. Planorbis hicarinatus striatus Baker. YII. This species was found in 

 the silt near shore and on the rocks off the islands of Lake Desor. 



29. Planorbis exacuous Say. II. A number of specimens were taken 

 among the leaves of submerged aquatic plants in Washington river. It 

 was also found on the rocks in shallow water about the islands of Lake 

 Desor, VII, and in Washington Harbor, X. 



30. Planorbis parvus Say. III. Collected among the leaves in the bed 

 of a dry creek in the deciduous forest. Also found in the rock pools on the 

 Minong Trap promontory, IX, and clinging to the rocks in shallow water 

 about the islands of Lake Desor, VII. 



31. Planorbis hirsutus Gld. This species was only found in Lake Desor, 

 VII, where it occurs on the rocks in shallow water about the islands. 



32. Valvata sincera lewisii Curr. VIII. A few^ specimens of this species 

 were found on the rocks in a back water pool at Siskowit Bay. 



33. Anodonta marginata Say. VII. Several specimens were collected 

 in shallow water at the west end of Lake Desor, among a scattered vegetation 

 of equisetum and water lilies. This is the only place where mussels were 

 found on the south end of the island, with the exception of a broken shell 

 in Washington Harbor, X, although a careful search was made for them 

 about the shore of the harbor and in Washington river. 



34. Pisidium abditum Hald. var. II. Several specimens were col- 

 ected among the wet fallen leaves in the alder thicket, on the bank of Wash- 

 ington river. 



i 35. Pisidium variabile Pme. 11. Among the leaves of a submerged 

 aquatic plant in Washington river. 



36. Pisidium sp. Pisidia which could not be identified were collected 

 on water plants in Washington river, II; in the silt in the bottom of Wash- 

 ington creek running through the arbor vitae swamp, IV, and in the debris 

 in the bottom of Grace creek, near its mouth. 



The following general observations on the collection will call attention 

 to the specimens of special interest and to their faunal affinities. So far 

 as Isle Royale is concerned, the fauna is purely boreal; the land species, 

 as far as they go, are the same (with one exception) as those of the Porcu- 

 pine Mountains, Ontonagon County. The only species not found in Onton- 

 agon County is Pijramidula striatella Anth. The occurrence of the 

 typical form of striatella on Isle Royale while the Ontonagon County 

 form is uniformly var. catskillensis Pils., is very curious. Catskillensis 

 is the characteristic form of Northern Michigan. It has been traced 

 from' Beulah, Benzie County, Mich, north through the Grand Trav- 

 erse region, Mackinac Island and the St. Mary's river, to Marquette, 

 Baraga and Ontonagon Counties. At Charlevoix both forms occur, while 

 specimens from Crooked Lake, Emmet County, are rather intermediate. 

 On the main land of the Upper Peninsula thus far only the variety has been 



found. 



Among the aquatic species, however. Isle Royale furnishes some interest- 

 ing forms. The form of Limnaea stagnalis is a peculiar and well marked 



