ECOLOGY OF ISLE ROY ALE. 281 



ANNOTATED LIST OF THE MOLLUSCA OF ISLE ROYALE, MICH- 

 IGAN. 



BY BRYA>!T WALKER. 



1. Introduction. 



This list contains all the species of molluscs collected on Isle Eoyale, 

 both in 1904 and 1905, and so represents the complete fauna so far as 

 known. For the details as to the localities represented by the col- 

 lection made in 1904, Reference should be made to the Report of that 

 expedition (pp. 96-99). 



The collection made in 1905 was much larger than that of the preced- 

 ing year, both in species and individuals. While eleven of the species 

 collected in 1904 were not found in 1905, no less than forty-two ad- 

 ditional species were obtained, making the total number of species now 

 known from the island seventy-two. The species added in 1905 are in- 

 dicated by an * on the list. In compiling the completed list, it has 

 been deemed of sufficient interest to add both the general range of 

 each species and its distribution so far as known in the state of Mich- 

 igan. 



2. Faunal Affinities. 



The molluscan fauna of Isle Eoyale becomes of additional interest 

 when considered in conection with Dr. W. H. Dall's recent work on the 

 "Land and Fresh. Water Mollusks of Alaska and Adjoining Regions," 

 (Harriman Alaska Expedition, Vol. XIII, 1905), which is a complete 

 digest of our present knowledge of the land and fresh water mollusca 

 of North America north of latitude 49° North, and practically of our 

 entire boreal fauna. So far as available, the general range of the species 

 given in that work has been followed in this list as being the most "up- 

 to-date" attainable. 



Of the seventy-two species recognized from Isle Eoyale, forty-nine 

 are included by Dr. Dall in his list of boreal species. 



The remaining twenty-three species not cited by him are: 



StroMlops virgo (Pils.) 



Vertigo tridentata Wolf. 



Euconulus chersinus polygyratiis Pils. 



Zonitoides exigua (Stimp.) 



AgrioUmax campestris (Say). 



Pallifera hemphilli (W. G. Binn.). 



Pallifera dorsalis (Binn.). 



Lymnwa pilsiryana Walker. 



Physa scuyii Tapp. 

 ' Physa aplectoides Sterki. 



Ancylus sp? 



Amnicola lustrica Say. 



Musculium seciiris Prime. 

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