Argynnia scotica Brown, 1911

Diagnosis: Shell compressed, broadly pyriform, with rounded fundus, which contracts abruptly into a short thick neck with lateral margins narrowing slightly to the borders of the mouth. In lateral view the fundus is rounded, and the sides slope gradually to the aperture with only very slight concavity. Aperture broadly elliptical with an irregular margin and no lateral notches. Shell surface somewhat variable, sometimes inclined to irregularity, covered with transparent, colourless scales, occasionally almost rounded, at other times irregular in shape, of very variable size, and sometimes distinctly overlapping, with smaller scales overlying the corners where three or four scales meet. All the plates appear corroded and the corners rounded, and cannot be confused therefore with mere foreign particles. Their general appearance and arrangement suggest A. dentistoma and A. vitrea. from which, however, this species differs in other respects. The apertural scales are frequently larger than the others, and by their shape give the irregular margin to the aperture.

Dimensions: Length 78-82 µm; width 57-59 µm; thickness 40 µm; mouth 18-19 µm.

Habitat: Freshwater. Sphagnum. Brown, 1911: “This species was found in large numbers in Sphagnum gathered from the middle slopes o£ Ben Ledi (Perthshire, Scotland) in August 1910.”