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Montana Field Guide

Montana Field Guides

Blue Glass - Nesovitrea binneyana
Other Names:  Retinella binneyana, Polita binneyana, Hyalina binneyana

Native Species

Global Rank: G5
State Rank: S5

Agency Status


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General Description
A small shell, to 3.7 mm diameter and 2.0 mm in height, flattened heliciform with a low spire, surface with narrow and widely spaced axial grooves, microscopic spiral striae, about 3 1/2 to 4
whorls, the last rapidly increasing in width. Shell coloration is glossy translucent to transparent, nearly colorless with a pale greenish tinge. Aperture is oblique, crescent-shaped, wider than tall, and without teeth (denticles), lip not thickened, periphery rounded; umbilicus relatively narrow, about 1/5 the shell diameter. Animal is pale grayish on the head and tentacles (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1946).

The subspecies in Montana is N. b. occidentalis.

Diagnostic Characteristics
A combination of small size (< 5.5 mm diameter), narrow umbilicus, small number of whorls (3.5 to 4.0), whorls increasing in size with the last obviously enlarged, transparent and shiny shell lacking spiral striations or riblets, distinguish Nesovitrea from other genera. N. binneyana differs from N. electrina by having a shell diameter < 4.0 mm, shell colorless to pale greenish, and the live animal pale grayish on head and tentacles.

Species Range
Montana Range Range Descriptions


Range Comments
Native to North America from British Columbia to Quebec and Maine, south through the Cascade Mountains to California, in the Rocky Mountains to Colorado. In Montana, reported on both sides of the Continental Divide from 19 counties. Elevation range is 917 to 2048 m (3010 to 6720 ft). Appears to be uncommon in most locations; nine were reported at a site in Jefferson County in late September (Hendricks 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 72

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Occupies a variety of forested habitats. Canopy species include Douglas-fir, Engelmann spruce, western redcedar, grand fir, western larch, ponderosa pine, lodgepole pine, aspen, and black cottonwood; secondary canopy includes alder, willow, paper birch, mountain maple, and hawthorn. Often found under woody debris, rocks, bryophyte mats, in leaf litter or duff (Hendricks 2012).

  • Literature Cited AboveLegend:   View Online Publication
    • Burke, T. E. 2013. Land snails and slugs of the Pacific Northwest. Corvallis, OR: Oregon State University Press. 344 p.
    • Hendricks, P. 2012. A Guide to the Land Snails and Slugs of Montana. A report to the U.S. Forest Service - Region 1. Montana Natural Heritage Program, Helena, MT. vii + 187 pp. plus appendices.
    • Pilsbry, H.A. 1946. Land Mollusca of North America (north of Mexico), Volume II Part 1. Academy of Natural Sciences of Philadelphia Monograph Number 3 (2):1-520.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Beetle, D. E. 1961. Mollusca of the Big Horn Mountains. The Nautilus 74:95-102.
    • Beetle, D.E. 1989. Checklist of recent Mollusca of Wyoming, U.S.A. The Great Basin Naturalist 49(4):637-645.
    • Berry, S.S. 1919. Mollusca of Glacier National Park, Montana. Proceedings of the Academy of Natural Sciences of Philadelphia 71:195-205.
    • Forsyth, R.G. 2004. Land snails of British Columbia. Royal British Columbia Museum: Victoria, British Columbia, Canada. 188 pp.
    • Frest, T.J. and E.J. Johannes. 2001. An annotated checklist of Idaho land and freshwater mollusks. Journal of the Idaho Academy of Science 36(2):1-51.
    • Russell, R.H. and R.B. Brunson. 1967. A check-list of molluscs of Glacier National Park, Montana. Sterkiana 26:1-5.
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Citation for data on this website:
Blue Glass — Nesovitrea binneyana.  Montana Field Guide.  .  Retrieved on , from