204 PROCEEDINGS OF THE ACADEMY OF [Oct., 



Vitrina alaskana Dall. 



Noted frequently as indicated in the table, but nowhere observed 

 in any abundance. 



Vertigo modesta parietalis (Ancey). 



The shells of this series show considerable variation. In some 

 cases a considerable proportion of the shells (a respectable minority 

 of those from Station XII, and a large majority of those from Sta- 

 tions I, II, and IX) have the angular lamella reduced to a mere trace 

 or obsolete, thus approximating the typical modesta. Somewhat 

 less than a third of all the adult shells taken are of this type, the 

 balance being distinctly 5-toothed shells, i. e., true parietalis. 



This Vertigo is abundant at suitable stations all through such 

 portions of the Park as were visited. 



Pisidium abditum Haldeman. 



The specimens were hand picked from a small and very cold pool, 

 but a few score feet from the partly frozen and perpetually frigid 

 Iceberg Lake, at 6000 feet altitude, the highest elevation at which 

 any Mollusca were obtained in the Park. Here they were abundant, 

 and with a small sieve of the proper mesh many specimens could 

 have been taken. 



The specific determination is due to Mr. Vanatta. 



Literature Cited. 



Baker, F. C. 



:14. Northern Idaho shells. Nautilus, v. 27, p. 104-106, January, 1914. 

 Dawson, G. M. 



'75. Land and fresh water Mollusca, collected during the summers of 1873- 

 1874, w^ ihe vicinity of the Forty-ninth Parallel — Lake of the Woods to the Rocky 

 Mountains. British North American Boundary Commission, Report on the 

 Geology and Resources of the region in the vicinity of the Forty-ninth Parallel, 

 etc.. Appendix E, p. 347-350, 1875. 

 Elrod, M. J. 



:02. A biological reconnaissance in the vicinity of Flathead Lake. Bulletin 

 University of Montana, No. 10, (Biological Series No. 3), p. 1-182, text fig. 1-3, 

 pi. 17-46, Missoula, 1902. 

 Morse, E. S. 



'64. Observations on the terrestrial Pulmonifera of Maine, including a cata- 

 logue of all the species of terrestrial and fluviatile Mollusca known to inhabit the 

 state. Journal Portland Society Natural History, v. 1, p. 1-63, text fig. 1-104, 

 pi. 1-10, 1864. 



PiLSBRY, H. A., AND FeRRISS, J. H. 



:10. Mollusca of the Southwestern States. IV. The Chiricahua Mountains, 

 Arizona. Proceedings Academy Natural Sciences Philadelphia, 1910, p. 44- 

 147, text fig. 1-36B, pi. 1-14, April, 1910. 

 Vanatta, E. G. 



:14. Montana shells. Proceedings Academy Natural Sciences Philadelphia, 

 1914, p. 367-371, text fig. 1-2, June, 1914. 



