Prof. Nicholson — Progress in Pakeontology. 9 



covery as regards the Brachiopoda that a small Carboniferous 

 species of Froducta was in the habit of arttaching itself firmly to 

 foreign bodies by means of the spines of the ventral valve. In this 

 department, also, Mr. Davidson still continues to publish the series 

 of supplements which will at last complete his magnificent " Mono- 

 graph of the British Fossil Brachiopoda." 



The proposal has recently been made, and has met with the 

 approbation of many eminent zoologists, to remove the groups 

 of the Polyzoa and the Brachiopoda to the group "Vermes," and to 

 place them in the neighbourhood of the Annelida. The grounds 

 upon which this step is advocated are derived wholly from the 

 study of living forms, and, indeed, are principally based upon the 

 similarity observed in the developmental processes of these animals. 

 This change, however, is hardly likely to be accepted save by 

 those who believe that Embryology is the real key to classification, 

 and it certainly is not at present supported by any evidence afforded 

 by the study of the fossil forms of Polyzoa and Brachiopoda. 



As regards the higher Mollusca, an immense mass of valuable 

 material has been accumulated in recent years by the elforts of many 

 patient and able observers. It would take up too much time, were 

 I to attempt to enumerate even the more important contributions 

 which have been made within the last decade to this department of 

 palaeontology. I cannot, however, forbear a passing allusion to the 

 great work on the " Invertebrate Cretaceous and Tertiary Fossils of 

 the Upper Missouri Country," published last year by Professor 

 Meek — a work which is not only in itself one of the most important 

 contributions ever made to the history of the fossil Mollusca, but the 

 appearance of which was followed, almost immediately, by the 

 lamented death of its distinguished writer. 



Passing on to the Vertebrates, we may notice the important light 

 which has been thrown upon the past history of Fishes, by the dis- 

 covery of two living species of Ceratodus in the rivers of Queens- 

 land. . From this discovery we are enabled to speak with certainty 

 as to the structure and affinities of the Ceratodi of the Trias, upon 

 which Agassiz originally founded the genus, and which were only 

 known by their curious dental plates. We are further enabled to 

 vastly extend backwards the range of the Dipnoous Fishes in time, 

 for this order, formerly believed not to occur in a fossil condition, is 

 probably represented by the Ctenodus of the Carboniferous and the 

 Dipterus of the Devonian, and it seems not unlikely that others of 

 the so-called " Ganoids " of the Palaeozoic period will ultimately 

 turn out to be truly referable to the Dipnoi. 



As regards the Amphibia, large accessions have been made to our 

 knowledge of the Labt/rinthodontia, chiefly through the researches 

 of Cope, Miall, Atthey, etc. The first named of these observers 

 has, in particular, described a large number of new and interesting 

 forms of this extinct group from the Coal-measures of Ohio, de- 

 scriptions and figures of which are to be found in the second volume 

 of the Paleeontology of Ohio. I may also add that we seem now in 

 possession of sufficient evidence to justify us in asserting that 



