These animals also escape detection by a very extraordinary, chameleon-like power of changing their colour.
They appear to vary their tints according to the nature of the ground over which they pass: when in deep water, their general shade was brownish purple, but when placed on the land, or in shallow water, this dark tint changed into one of a yellowish green.

The colour, examined more carefully, was a French grey, with numerous minute spots of bright yellow: the former of these varied in intensity; the latter entirely disappeared and appeared again by turns.

These changes were effected in such a manner that clouds, varying in tint between a hyacinth red and a chestnut-brown, were continually passing over the body.

(1/4.

So named according to Patrick Symes's nomenclature.) Any part, being subjected to a slight shock of galvanism, became almost black: a similar effect, but in a less degree, was produced by scratching the skin with a needle.