President's Address. 159 



Tenth Decade. Mr Powrie has also himself contributed 

 several papers on the fishes of these beds, and to liim we owe 

 the definition of the genus Euacantlms, comprising four 

 species, and also of a new species of Parexus. 



The remarkable group of Cephalaspidcv, so characteristic of 

 the Old Eed Sandstone in particular localities, has been ably- 

 monographed by Professor E. Eay Lankester, whose work, in 

 two parts, appeared in the volumes of the Palseontographical 

 Society for 1868 and 1870. 



The true affinities of the Old Eed Sandstone genus Dipterus, 

 and the carboniferous Ctenodus, foreshadowed by Professor 

 Huxley in 1861, were thoroughly cleared up by the discovery 

 of the living Ceratodus Forsteri in the rivers of Queensland. 

 The Ctenododipterini were definitely placed among the Dipnoi 

 by Dr Gunther in his account of the structure of Ceratodus 

 (Phil. Trans., 1871), and subsequent observation has amply 

 confirmed the correctness of his views on this point. 



The discovery in the Devonian rocks of North America of 

 the gigantic Placoderm, named by Professor Newberry 

 Dinichthi/s, seems at last to throw some light on the position 

 of that remarkable group of extinct fishes. In Dinichtliys 

 we have a form, apparently closely allied to Coccostens, but 

 also possessed of a dentition in many respects resembling 

 that of the recent Zepidosiren. It seems, therefore, not 

 unlikely that the Placodermata will eventually turn out to 

 have been an aberrant group of loricated Dipnoi. 



Eecent progress with regard to the structure and affinities 

 of Scottish Carboniferous fishes is so inseparably connected 

 with the study of the fishes of the same great period in 

 England, that here the sister kingdoms cannot easily be 

 treated separately, except as regards local and stratigraphical 

 lists of genera and species. Descriptive papers dealing with 

 English specimens are of equal importance to the student 

 resident in Scotland. Scottish fossil ichthyology is therefore 

 equally indebted to Professor Young for his descriptions 

 (published in 1866) of the remarkable Platysomid genera 

 Amphicentrum (= Cheirodus, M'Coy) and Mesolepis, as well 

 as of the little Platysomus parvulus, a species named but not 

 described by Agassiz, as all of them occur in the Scottish 



