Angle of palatal (outer) lip with edge of siphonal canal:

obtuse on T. nitida 120° (1 & 2), 115° (3),

acute or right angle on T. reticulata 80° (4), 90° (5).

Shell 4 was the only T. reticulata in a sample of 220 beached shells from the Blackwater estuary>; all others were T. nitida. This site is close to where Jeffreys found and first described T. nitida.

1 to 4: Blackwater, Essex, England, September 2019, leg. S.Taylor. 5: West Anglesey, Wales, March 2014.