ECOLOGY OF NORTHERN MICHIGAN. 97 



the deciduous forest, III, among the damp fallen leaves and under rocks; 

 in the humus of the cedar swamp, IV; in the moss in the tamarack swamp, 

 V, and in the moss among the heath plants on the Minong Trap promon- 

 tory, IX. 



11. Pyramidula striatella, alba (Walker). II. In the moss forming the 

 ground cover of the coniferous forest. III. Several specimens were also 

 collected among the damp fallen leaves in the deciduous forest. 



12. Pyramidula asteriscus (Mse.). III. Taken among the fallen leaves 

 in a moist ravine in the deciduous forest. 



13' Acanthinula harpa (Say). II. This species was found to occur in 

 the moss ground cover of the coniferous forest bordering Washington river; 

 in the humus of the arbor vitae swamp, IV, and in the moss about the roots 

 of the heath plants on the Minong Trap promontory, IX. 



14. Punctum pygmaeum -(Drap.). III. Several specimens of this form 

 were collected among the damp fallen leaves in the deciduous forest. 



15. Sphyradium edentulum (Drap.). II. Beneath the bark of a fallen 

 log in the coniferous forest along Washington river, and among the fallen 

 leaves in the deciduous forest, III. 



16. Euconulus fulvus (Drap.). This shell was found beneath the bark 

 of a fallen birch tree in the coniferous forest, II; among the fallen leaves 

 in the deciduous forest, III, and in the moss of the tamarack swamp, V. 

 A few dead shells were also found in the sediment in the bottom of Grace 

 creek. 



17. Euconulus chersinus polygyratus (Pils.). Collected in' the moss and 

 decaying logs in the coniferous forest on the flood-plain of Washington 

 river, II; among the fallen leaves in the deciduous forest, III, and beneath 

 the bark of a decaying tamarack stump, V. 



18. Vertigo ovataf Say. A defective specimen was found in the humus 

 of the arbor vitae swamp, IV. 



19. Vertigo gouldii Binn. Among the fallen leaves in the deciduous 

 forest, III, and in the moss of the tamarack swamp, V. 



20. Vertigo sp. In the moss about the foot of a tamarack, V. 



21. Carychium exile H. C. Lea. This species was found among the 

 fallen alder leaves on a very wet flat along Washington river, II, and among 

 the fallen maple leaves in the deciduous forest, III. 



22. Limnaea stagnalis L. var. This snail is very abundant about the 

 shores of Washington Harbor, X. The specimens collected were attached 

 to the larger rocks that are not readily moved by the action of the surf. 



23. Limnaea n. sp.? (related to L. sumassi Bd., but probably undescribed) . 

 X. This form is also abundant in Washington Harbor, and with Limnaea 

 stagnalis constitutes the characteristic molluscan life of this station. 

 The specimens collected were found clinging to the rocks under the same 

 conditions as L. stagnalis. It was also found to occur commonly in the 

 rock pools on the Minong Trap promontory, IX. 



24. Physa sayii Tapp. var. X. This form was found only in Washing- 

 ton Harbor, where it occurs on the rocks near shore. 



25. Physa sp. (probably sayii Tapp.). VIII. A few specimens were 

 found at Siskowit Bay, attached to stones in the back water pools on the 

 beach. 



26. Physa sp. Under this head are grouped a number of immature 

 ^shells jcollected in Lake Desor, VII, in the fine silt near shore and attached 

 to large rocks about the islands; among the leaves of submerged aquatic 



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