ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxi 



longer limbs, and with a wide, laterally compressed tail : its habits 

 were probably aquatic. 



" The quadrupedal foot-tracks discovered by Capt. Lambart Brick- 

 enden, resemble those usually ascribed to terrestrial or lacustrine 

 Chelonians. 



" The Stagonolepis Robertsoni, Agassiz, the only other organism 

 found in the same rock, is a ganoid fish, with sculptured scales, closely 

 resembling the Old Red Sandstone genus Glyptopomus, Agass." 



You will also recollect that Mr. Logan has communicated to us 

 during the past year a notice of the discovery of foot-prints in the 

 Potsdam Sandstone of North America. Prof. Owen considers them 

 to be either Batrachian or Chelonian. These are facts of especial 

 interest, as indicating the existence of vertebrate animals in an early 

 portion of the Silurian period. Mr. Logan has recently brought 

 over from Canada some large slabs with the foot-marks upon them, 

 and an extensive series of casts of others, now exhibited in the Mu- 

 seum of our Society. The removal of slabs of such magnitude has 

 not been accomplished without considerable expense and great labour ; 

 and we are bound to express to Mr. Logan our obligation to him for 

 the zeal and energy he has shown in thus placing these magnificent 

 specimens within our reach. 



The discovery in a single year of so much incontrovertible evidence 

 of the extension of reptilian remains into some of the lowest fossili- 

 ferous strata is very remarkable, and calculated to add greatly to the 

 interest of the discussion of the theory of the progression of organic 

 forms during successive geological epochs, which has lately occupied 

 the minds of geologists. 



It will be recollected that the advocates of the doctrine of progres- 

 sion, as well as the distinguished geologist who has been their princi- 

 pal opponent, distinctly repudiate the idea of the progression here 

 spoken of involving any notion of the transmutation of species, a 

 theory to which, as you well know, they have been most strongly 

 opposed. They merely assert their belief that there has been upon 

 the whole " a gradual ascent towards a higher type of being*," from 

 the earliest to the latest geological periods. They would also con- 

 tend for a certain progression in the physical state of our planet, " a 

 gradual improvement in the style and character of the dwelling-place 

 of organized beings f." These are the propositions which your late 

 distinguished President combated in the two Addresses which he 

 delivered from this chair. 



It would be absurd to contend that either the first of these pro- 

 positions or its negative have been yet established by demonstrative 

 evidence. The advocate of progression can only reason on the con- 

 fessedly imperfect evidence which we at present possess respecting the 

 extent and variety of organic beings which existed at the earliest geo- 

 logical period to which we can refer the organic remains with which 

 we are acquainted ; and so far as his opponent proves to us more 

 clearly the incompleteness of this evidence, and thus inspires us with 



* Prof. Sedgwick, * Discourse on the Studies of Cambridge,' Preface, p. cliv. 

 t Mr. Hugh Miller, ' Foot-prints of the Creator.' 



