.3,3. NOTES AND COMMENTS. 91 



and it is stated that the new specimens serve to indicate more conclu- 

 sively than hitherto the relationship of that group to the Monotremes, 

 although this is not very apparent from the descriptions. The other 

 remains belong to Marsupials, which are considered to be most nearly 

 related to the living opossums. 



It is not often that ordinary text-books are in advance of current 

 thought, but Mr. Arthur Thomson's Outlines of Zoology, which we 

 review elsewhere, contains one bold statement that we commend to 

 the notice of those interested in the classification of vertebrated 

 animals. The author remarks: "What the 'worms' are among 

 Invertebrates, the Reptilia are among Vertebrates — an assemblage of 

 classes." Unfortunately, nearly all the more important forms of 

 reptiles are extinct, and they are thus known only by skeletons ; but 

 that they are a medley of widely distinct groups is becoming very 

 evident. As shown more especially by the researches of Cope, 

 Marsh, and Seeley, the early extinct " Reptilia" (including the 

 Labyrinthodonts) form the base of at least four widely divergent lines 

 of evolution — the modern Batrachia, the modern Reptilia, Birds, and 

 Mammals. The formal dismemberment of the " class " may be only 

 a question of time. 



Although known now for twenty years, it is remarkable how 

 little information has been added to our knowledge of the Australian 

 Mud-fish, Ceratodus, since its original description by Dr. Giinther, 

 and the subsequent notes by Professor Huxley. At the meeting of 

 the Australasian Association in Hobart Town last January, Professor 

 Baldwin Spencer returned to the subject, describing some of the 

 habits of the animal ; but, judging from the brief report to hand, he 

 had little new to communicate. It is suggested that the lung-like 

 air-bladder of Ceratodus is of special use to the fish at times of floods, 

 when the water in which it dwells is charged with much sediment ; 

 and there is no evidence that Ceratodus ever leaves its native element, 

 being in this respect unlike its African ally, Protopterus, which 

 lives coiled up in a " cocoon " in dry mud during the hot season. It 

 is of the greatest importance from the philosophical point of view 

 that we should have some detailed memoirs on the embryology of 

 Ceratodus, and to us it is inexplicable that none of the able biologists 

 in Australasia have yet accomplished so important a research. 

 Nearly ten years ago Mr. Caldwell, of Cambridge, made the collection 

 of the embryos of Ceratodus one of the special objects of his mission to 

 Australia, towards the expenses of which both the Royal Society and 

 the University of Cambridge contributed funds ; yet, so far as we 

 are aware, there are at present no scientific results. Specimens 

 collected at public expense ought to be public property, and if the 

 naturalist who does this service loses his enthusiasm or undertakes 



