308 NATURAL SCIENCE. April, 



The Australian Mud-Fish. 



Travels for Zoological Research in Australia and the Malay Archi- 

 pelago. [Zoologische Forschungsreisen in Australien und dem malayischen 

 Archipel.] Pts. I. II. Edited by Richard Semon. Jena : Gustav Fischer, 1893. 



The munificence of Dr. Paul von Ritter, founder of the Professorship 

 of Phylogeny and Theories of Descent at Jena, has already rendered 

 signal service to Biological Science. We have often referred to the 

 researches of the Ritter Professor, Dr. W. Kiikenthal, which are of 

 fundamental importance for the understanding of the vertebrate 

 animals. We now have to welcome the first instalment of another 

 great work rendered possible by the same generous patron. Between 

 June, 1 89 1, and the end of the following year, Professor Richard 

 Semon, of the University of Jena, was enabled to undertake one of the 

 most important scientific expeditions for collecting that has hitherto 

 been made, to Australia and the Malay Archipelago. Now, the 

 collections have been assorted and arranged, and the publication of 

 the results is commenced in a series of fine quarto volumes. 

 Dr. Semon estimates that there will be five volumes devoted to the 

 Vertebrata, the first relating to the Ceratodns, the second and third to 

 the Monotremes and Marsupials, the fourth and fifth to Sirenians, 

 Edentates, Amphioxtis, and miscellaneous other types. 



Professor Haeckel appropriately prefaces the work with some 

 general observations on the relationship of the Australian Fauna, 

 and then Dr. Semon contributes a brief sketch of his journey, 

 enumerating the various centres at which collections were made. 

 Biologists, howei'er, will turn at once with greatest interest to the 

 first part of Dr. Semon's detailed monograph of Ceratodns, which is 

 destined to inaugurate a new era in our knowledge of the recent mud- 

 fishes. As patriotic Britons we peruse it with mingled feelings ; for 

 had not the collector despatched ten years ago by the Royal Society 

 of London and the University of Cambridge betrayed his trust, the 

 credit of unravelling these problems would have belonged to our own 

 nation. 



It is impossible to do justice to Dr. Semon's work on the 

 Australian mud-fish in a brief notice ; and it is too early to discuss 

 the conclusions, only the first stages in the life-history of the animal 

 being as yet described in a general way. The facts in reference to 

 the distribution, mode of life, and propagation of Ceratodns are set 

 forth in a more exhaustive manner than by previous observers ; 

 and the embryological part is illustrated by exquisite plates of 

 segmenting eggs and of immature fishes. Ceratodns is believed to be 

 confined to the Burnett and Mary rivers, Queensland ; and although, 

 as already generally known, it crops the vegetation with its great 

 teeth, the most important part of its food consists in the small 

 animals living between the fronds and leaves. It seems to be quite 

 powerless to move on land, and it never lies dormant in "cocoons." 

 The eggs are laid separately and loosely among the vegetation ; the 

 fore-limbs begin to appear at the end of about fourteen days, and 

 the hind-limbs not before two-and-a-half months. In the course of 

 development, Ceratodns presents most resemblance to the Cyclostomes 

 and the Amphibia; but it is noteworthy that external gills are absent 

 at all stages, and there is no trace of a suctorial mouth. There is no 

 rudiment of a connection between the pectoral and pelvic fins ; and 

 many features are entirely peculiar. The large dental plates result 

 from the fusions of small teeth, exactly as might have been expected 

 from what is known of extinct mud-fishes. As to the all-important 



