Since the sending in of my last communication, that on the Skull of the Fowl, our knowledge of the morphology of the facial arches has been very greatly extended by Professor Huxley’s invaluable paper “On the Representatives of the Malleus and the Incus of the Mammalia in the other Vertebrata” (see Proc. Zool. Soc. May 1869, pp. 391-407). After comparing the components of the mandibular and hyoid arches in an extended series of vertebrate types, the author concludes his paper by saying (p. 406), “in the higher Amphibia changes of a most remarkable kind take place, of which I do not now propose to speak, as my friend Mr. Parker is engaged in working out that part of the subject.”