THE cells of Mauthner occur in the medulla oblongata of many teleost fishes, Dipnoi and urodele Amphibia, where they have been widely studied. On the other hand, their occurrence in the larvae of anuran Amphibia has been disputed for many years, and to judge from the literature most attempts to find them have failed. Szepsenwol1 claims to have found them in the larvae of Ranafusca and Bowbinator pachypus ; but his account, unfortunately published without illustration, does not appear to have received general recognition.