Charles S. Boyer, Diatomaceae of Philadelphia — Biddulphioideae (1916)
“ Frustule quadrangular, elevated at the angles into subconical processes oblique to the longitudinal axis. Valve triangular or quadrangular, plane, of two layers, the outer layer composed of large hexagonal cells in rows parallel to the sides, the inner of small puncta radiating from the centre. ”
Charles S. Boyer, Diatomaceae of Philadelphia — Biddulphioideae (1916)
“ Valve triangular, angles elevated into spines. Cells at the margin large. TRINACRIA PILEOLUS (EHR.) GRUN. Valve with concave sides. Surface concave with unequal punctiform and scattered markings with central dots. Cells at the margin large, rounded. At the angles, which vary in elevation, a few puncta are seen. ”
Charles S. Boyer, Diatomaceae of Philadelphia — Biddulphioideae (1916)
“ Valve orbicular, convex, with reticulations 5 in 10 μ radiating from the centre and decreasing toward the margin and processes which are truncate. A short spine is found on each side half way between the processes. Zone narrow with fine puncta 12 in 10 μ in longitudinal rows. ”
