932 NOTE ON A LABYRINTHODONT FOSSIL FROM COCKATOO ISLAND, 



one block of sandstone which had an unusual and evidently 

 important impression of some organic structure. The stone itself 

 was a rough conglomerate, with some large holes where pebbles 

 had fallen out, and a few fragmentary pieces of shale still embedded. 



When Mr. Wilkinson showed me the specimen, I recognised it 

 at once as a thoracic or throat-plate of Mastodonsaurus — probably 

 M. robustus, or at least very closely related to that species, — in 

 consequence of its exact resemblance to the fossil from the Uni- 

 versity collection which lies beside it on the table. We have not 

 the material here for an exact determination such as will be made 

 in England ; but there is and can be no question as to the Laby- 

 rinthodont character of the fossil, nor, as I believe, as to its 

 identification with some species of Mastodonsaurus. 



Now many considerations had induced the geologists of India 

 and Australia to class upon the same horizon the rocks of the 

 Upper Gondwana of India, the Upper Karoo beds of South Africa 

 and the Hawkesbury-Wianamatta beds of East Australia, with, 

 the Keuper and Rhsetic or Upper Triassic beds of Europe. 



But the evidence so far as Australia was concerned was not 

 quite satisfactory, although increasing year by year ; and I cannot 

 but think it a very happy coincidence that this Amphibian should 

 have turned up immediately after Mr. Oldham's papers upon this 

 subject in the Geological Magazine. I do not intend to enter at 

 present into any arrangement of the facts which have been already 

 ascertained, since I am sure far more competent hands will soon be 

 at work upon the subject. There are, however, a few points to 

 which I may draw your attention with reference to the distribution 

 of the Amphibia, and the early Mesozoic Geography of Australasia 

 and New Zealand. 



It was remarked many years ago by Darwin, that these animals, 

 Batrachia or Amphibia, had a very closely restricted distribution 

 They are not able to bear contact with salt-water, and are 

 consequently absent from almost all oceanic islands. And of the 

 four great orders into which the class is divided, only one is at 



