442 MICHIGAN SURVEY— WALKER. 



SUMMARY. 



F. W. F. W. 



Land. Pulmonates. Operculates. Bivalves. Total. 



Sager 1839 23 10 4 28 65 



Miles 1860 42 23 12 56 133 



Currier 1868 45 36 12 47 140 



DeCamp 1881 49 30 25 63 167 



Walker 1894 68 46 29 82 225 



Walker 1905 78* 51 31 112 272 



II. 



THE TERRESTRIAL MOLLUSCAN FAUNA OF MICHIGAN. 



According to W. G. Binney, all that part of the continent east of the 

 Rocky Mountains and north of Mexico, forms a single Zoological province 

 known as the Eastern Province. This again is divided into three regions: 

 Northern, Interior, and Southern. The Northern Region comprises British 

 America and that part of the United States lying east of the Appalachian 

 chain of mountains, while the Interior Region extends from the north region 

 south to the alluvial lands lying along the Gulf of Mexico. Roughly speak- 

 ing, the dividing line between the Northern and Interior Regions west of 

 the Appalachian chain is the political boundary between Canada and the 

 United States. But practically there is no hard and fast dividing line, 

 and one region gradually merges into the other. 



According to Merriam, the upper peninsula and the northern part of the 

 lower peninsula lying east of the Grand Traverse region, and north of Iosco 

 county, belong to the Boreal Zone. 



The Lake Michigan shore as far north as the mouth of Grand Traverse 

 Bay and the entire southern part of the state, lying south of (approximately) 

 the north line of Jackson, Washtenaw and Wayne counties are included in 

 the Upper Austral Zone, while the remainder of the state, lying between 

 these, including the Grand Traverse region, form part of the Transition 

 Zone. 



Of the twelve species given by W. G. Binney as being universally distrib- 

 uted over North America, all are found in Michigan, and nearly all of them 

 are among our most common and abundant forms. They are: 



Pyramidula cronkhitei anthonyi (Pih) . Vitrea hammonis (Strom). 



Punctum pygmceum (Drap). Vitrea indentata (Say). 



Helicodiscus parallelus (Say). Zonitoides nitida (Mull). 



Vallonia pulchella (Mull). Zonitoides arhorea (Say). 



Pupilla muscorum (L.) Zonitoides minuscula (Binn.) 



Eiiconulus fulvus (Mull).t Zonitoides milium (Mse). 



Of the species considered by the same author as characteristic of the 

 Northern Region, twelve are represented in our fauna, viz.: 



* An additional species, Omphxlini inornata, has been authenticated sinc^ this synopsis was pub- 

 lished making the present number 79. In this table the species of Carychium are included in the 

 F. W. pulmonates. 



t Since the recent revision of this genus by Pilsbry this species would scarcely fall within this 

 category. 



