COMPARISON of valve arch profiles of three species. All viewed from posterior of valve iv.
Height/Width% varies in all three species and their elevation ranges overlap.
Kaas & Van Belle in Schwabe define elevations (h/w) of valve iv as:
low if less than 25%, moderate 25% to 45% and high if over 45%.
T. marmorea
1, 2,3 ELWS Isle of Lewis, Scotland. April 2018. Leg. D. McKay & S.Taylor.
4 ELWS Orkney, Scotland. 1974. Leg. I.F.Smith.
1: animal 32mm long. H/W 30%, moderate elevation.
2:29mm long. H/W 33%, moderate elevation.
3: 32mm long . H/W 29%, moderate elevation.
4: 15.3mm long . H/W 20%, low elevation.
Kaas & Belle (1985) text & image H/W 37%, moderate elevation. N.E, Atlantic
The side slopes of valves ii to vii are straight (7:) or slightly convex (8:) when viewed from the anterior or posterior.
Boreochiton ruber
N. Yorkshire 2014. Leg. P. Lightfoot.
5: animal 14.5mm long. H/W 23%, low elevation.
H/W varies and overlaps T. marmorea range.
Lepidochitona cinerea
6: H/W 32%, moderate elevation.