ECOLOGY OF NORTHERN MICHIGAN. 93 



ANNOTATED LIST OF THE MOLLUSCS OF THE PORCUPINE MOUN- 

 TAINS AND ISLE ROYALE, MICHIGAN. 



BRYANT WALKER AND A. G. RUTHVEN. 



This list has been prepared from the collections and field notes made 

 by A. G. Ruthven. The species of Pisidium, Sphaerium and Vertigo were 

 identified by Dr. V. Sterki, the Slugs by Dr. H. A. Pilsbry, and the re- 

 mainder of the collection by Bryant Walker. 



1. PORCUPINE MOUNTAINS. 



1. Agriolimax campestris (Binn.). This species was found among the 

 fallen leaves in the hardwood forest, II. 2, and under a pine log in the aspen 

 zone on the mountain top, III. 1. 



2. Pallifera hemphilli (W. G. Binn.). As represented by the collections, 

 this slug is quite generally distributed. It was found among the fallen 

 leaves in the deciduous forest, II. 2; beneath a fallen pine log in the pine 

 zone, III. 1, and under the bark of a tamarack log, IV. 4. 



3. Zonitoides arborea (Say). III. 1. A number of specimens of this 

 species were taken under fallen pine trees among the bearberry and huckle- 

 berry bushes in the aspen zone. IV. 4. Several specimens were found 

 beneath the bark of decaying tamarack and cedar logs in the tamarack 

 swamp. VI. A few specimens were taken in the moist humus about the 

 roots of ferns on the bank of Carp creek, and among the moist decaying 

 leaves on higher ground. 



4. Zonitoides milium (Mse.). III. 2. Individuals of this species were 

 collected in the dry earth about the roots of the New Jersey tea on the moun- 

 tain top; in the humus about the roots of an arbor vitae in the cedar swamp, 

 II. 1, and in the humus in the hemlock woods, II. 2. 



5. Zonitoides exigua (Stimp.). II. 2. A number of individuals were 

 found among the fallen leaves in the hemlock and maple woods. Several 

 were also found in decaying cedar and tamarack logs in the tamarack swamp, 

 IV. 4. 



6. Vitrea ferrea (Mse.) . IV. 4. A few individuals of this species were taken 

 in a fallen tamarack log in the peat bog. 



7. Vitrea indentata (Say). II. 2. Under dead moist leaves in the hard- 

 wood forest. III. 1. Under fallen logs and in the soil in the aspen zone on 

 the mountain top. III. 2. In the dry earth in crevices and held by the 

 roots of the heath plants on the bare mountain top, and among the roots of 

 the New Jersey tea in the aspen zone, III. 4. Also found under the bark 

 of fallen tamarack logs in the tamarack swamp, IV. 4. 



8. Vitrea multidentata (Binn.). III. 1. Several specimens were taken 

 under the bark of a fallen pine in the aspen zone at the top of the first range. 



9. Pyramidula alternata (Say). II. 3. Specimens of this form were 

 found crawling about on a log in the clearing, early in the morning while 

 the dew was heavy. 



10. Pyramidula striatella catskillensis Pils. THis species was collected 



