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Diatoms of the United States is now known as Diatoms of North America.
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The narrow, hyaline area on the valve mantle in the genus Aulacoseira. A small furrow, or sulcus, separates the collum from the portion of the valve mantle with areolae. See also ringleiste.


Barber, H.G. and Haworth, E.Y. (1981). Guide to the Morphology of the Diatom Frustule. Freshwater Biological Association, 112 pp.