At the Evening Meeting of this Society held on the 17th of November 1858, a paper by Mr. Stow “On some Fossils from South Africa” was read. In the course of the discussion which followed, my opinion as to the nature of one of those fossils was asked. With so much reserve as was due to the cursory character of my examination of the remains, I expressed my conviction that the organism in question was the skull of a Labyrinthodont Amphibian, and briefly stated the grounds upon which I based that conclusion. The Chairman of the Meeting then called upon me to undertake a thorough investigation of the matter; and I now report the results of my inquiries in the first of the following papers, in which I have embodied, incidentally, the description of an allied Australian Amphibian. 1. On Micropholis Stowii and Bothriceps Australis. Micropholis Stowii —The skull in question is 1 ⅝ inch long, and has, when viewed from above, a parabolic outline (Pl. XXI. fig. 1), or it might be compared to the half of a long ellipse, half of the longer diameter of which is to its shorter diameter as 13 to 10. The bony plates which formed the roof of the skull (fig. 1) have entirely disappeared, as have those which constituted the greater part of its right lateral parietes; but on the left side (fig. 2), the lateral walls are in a tolerably good state of preservation. The matrix has split in such a manner that that portion of it which is bounded by the contour of the skull