GYROSIGMA ATTENUATUM

MAKER: C.M. TOPPING.

STREW SLIDE c. 1850

This diatom was first named Frustulia attenuata by Kützing and arbitrarily renamed Navicula hippocampus by Christian Gottfried Ehrenberg in 1838. It was finally renamed Gyrosigma attenuatum by Gottlob Ludwig Rabenhorst in 1853 but the name Navicula hippocampus continued to be used for many years afterwards. The hallmark of this diatom is that, depending on the orientation of the lighting and the depth of focus, its longitudinal striae are more prominent than the transverse ones. This phenomena is not as obvious in the second image above as in the first. Both are from the same slide.

Another example of this diatom from a modern Klaus Kemp Type slide from about the year 2000 (not a strew) is shown here: