158 Proceedings of the Royal Physical Society. 



dosteidce, with the addition of the recent Amiadce, are equiva- 

 lent to Johannes Miiller's Ganoidei Holostei. The other 

 sub-order of the Berlin anatomist, that of the Chondrostei or 

 Sturgeons, was accepted, and to it the remarkable Old Red 

 family of Gephalaspidce was referred, provisionally at least ; 

 while into a fifth sub-order was erected the problematic group 

 of Acanthodidce, which, in their organisation, seem to combine 

 so many of the characters both of Ganoids and of Sharks. 



Undoubtedly, the weakest point in Professor Huxley's 

 "Essay" is the attempt which he made to show, by comparison 

 of the exoskeletal plates of Coccosteus with the bones visible 

 on the exterior of the skeleton of many recent Siluroids, that 

 there was a possibility at least of the enigmatical group of 

 Placodermata turning out to belong to the great order of 

 Teleostei, or ordinary bony fishes, " hitherto supposed to be 

 entirely absent from formations of Palaeozoic age." Recent 

 discoveries in the Palaeozoic rocks of America point, as we 

 shall presently see, to another, and perhaps more probable 

 solution of the question. 



The Twelfth Decade of the Geological Survey, published in 

 1866, contains a description, by Professor Huxley, of a 

 beautiful specimen of the Glyptodipterine Glypto'pomus minor 

 from the Old Red of Elgin, and also an exposition of the struc- 

 ture of the family Goelacanthidce as restricted in the celebrated 

 "Essay." Though the descriptions of Ccelacanthidce are 

 taken from English specimens of the family from the car- 

 boniferous to the chalk inclusive, they are equally important 

 as regards Scottish fossil ichthyology, as the remains of the 

 type-genus Gcelacanthus are of frequent occurrence in the 

 Carboniferous rocks of the northern part of our island. 



Professor Huxley's writings on fossil fishes supply us 

 indeed with a pattern of the method and spirit in which such 

 investigations should be conducted. Few in number as they 

 are, they have nevertheless contributed more to the real 

 scientific advancement of palaeozoic ichthyology than the 

 works of any other living author. 



I have already mentioned the name of Mr Powrie of Res- 

 wallie in connection with the beautiful Acanthodian fishes 

 from Forfarshire, figured by Sir Philip Grey-Egerton in the 



