Lyrella lyroides and Lyrella lyra

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Diatoms Lyrella lyroides and Lyrella lyra

The silicaceous tests (shells) of diatoms are a favorite subject for many microscopists due to their intricate designs. These two species are deceptively simple, L lyroides forming a simple pointed oval, whilst the L lyra looks like an elongated lemon in cross section. The centre is free of design but then two slits (raphes) run to the termini of the ovals. There is a narrow border of horizontal rows of dots (or punctae) around the slits and a wider border of horizontal ros around the edge of the diatoms. The overall patterning leaves a a clear area which looks like the shape of the ancient lyre, hence the name lyrella. Bernhard Hartley , the preparer of the slide from which this drawing was made, is a renowned expert on diatoms and has prepared the book 'An Atlas of British Diatoms' as an invaluable guide. It is composed of 6152 illustrations by H G Barber and J R Carter which are a class above what I can provide here. Many diatoms are radially or bilaterally symmetrical with very regular patterns and this is very difficult to reproduce in a drawing, just try to redraw the simple outline of these two diatoms freehand and you will appreciate what I mean! Balsam Post cover, issue No. 34, January 1997. Drawn from PMS box 93/12 by Bernhard Hartley.

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1992-2002 Contents

Balsam post 1992-2002 home

1992-2002 Cover index