Whittock, Nathaniel: The Art Of Drawing And Colouring From Nature, Flowers, Fruit, And Shells: To Which Is Added, Correct Directions For Preparing The Most Brilliant Colours For Painting On Velvet, With The Mode Of Using Them, Also The New Method Of Oriental Tinting ; With Plain And Coloured Drawings (London, 1829)

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The scallop is tinted with lake, interspersed with streaks of yellow
and blue; the markings on the shell are formed with indian red and
blue. It adds greatly to the effect of the drawing, if coral or sea-weed
are placed around the shells, as it breaks the lines, and makes them
more picturesque. Coral is perhaps the brightest scarlet in nature :
it can only be produced in colouring by laying on a tint of gamboge
before bright carmine or lake is applied.

LESSON XX.

THREE SHELLS, UNIVALVE.

The three shells forming the subject of this lesson, are as opposite
in their forms as possible; they are all univalve. The oval-shaped
spotted shell is a cowry, or in the language of the conchologist of
the genus cyprsea. This is the most common shell of the genus :
there are many of them exceedingly beautiful, but would be too diffi-
cult for a learner to execute till the one under notice has been