1. The rate of chromatic adaptation to background colour has been examined briefly in thirty-three species of teleost fishes (from nineteen families, eight orders) to test the presence of nervous control of chromatophores.
2. The same fishes have then been tested for chromatic responses to local heating or cooling of the skin.
3. Thermal responses resembling those of Phoxinus have been found in fourteen species which show quick adaptation, but not in thirteen other such species. No thermal responses have been found in any of the six species which do not show quick adaptation.
4. There appears to be no significance in the taxonomic distribution of these results and no new responses to temperature have been found.