A perpendicular section of several plates of whale bone in their natural situation in the gum.

Engraving depicting whalebone plates: on right ("Fig. 1"), a cross-section of whalebone embedded in the gum, and on left ("Fig 2.") an outline diagram showing the manner of growth of the plates, labelled with letters "a" and "B"-"E". Above is printed : "Plate LI. Phil. Trans. Vol. LXXVII Tab. XXIII p. 450" and below is printed artist attributions. A cutting from the source text has been pasted to the bottom right corner; the text reads,
"PLATE LI.
Fig.1. A perpendicular section of several plates of whalebone in their natural situation in the gum; their inner edges, or shortest terminations, are removed, and the cut edges of the plates seen from the inside of the mouth. The upper part shows the rough surface formed by the hairy termination of each plate of whalebone. The middle part shows the distance the plates of whalebone are from each other. The lower part shows the white substance in which they grow, and also the basis on which they stand.
Fig. 2. An outline considerably magnified, to show the mode of growth of the plates, and of the white intermediate substance.
A. The middle layer of the plate, which is formed upon a pulp or cone that passes up in the centre of the plate. The termination of this layer forms the hair. B. One of the outer layers, which grows, or is formed, from the intermediate white substance. CCCC. The intermediate white substance, laminae of which are continued along the middle layer, and form the substance of the plate of whalebone. D. The outline of another plate of whalebone. E. The basis on which the plates are formed, which adheres to the jaw bone."