Dr. A. S. Woodu-ard's Presidential Address. 415 



other words, there was a great outburst of Eurypterid life just at the 

 time when backboned animals arose ; and if some of the former were 

 actually transformed into the latter, the phenomenon took place when 

 their powers both of variation and of multiplication were at their 

 maximum. 



Fishes were already well established and distributed over perhaps 

 the greater part of the Northern Hemisphere at the beginning of 

 Devonian times ; and then there began suddenly a remarkable impulse 

 towards the production of lung-breathers, which is noticeable not 

 only in Europe and North America but also probably so far away 

 as Australia. In the middle and latter part of the Devonian period 

 most of the true fishes had paddles, making them crawlers as much 

 as swimmers ; many of them differed from typical fishes, while 

 agreeing with lung-breathers, in having the basis of the upper jaw 

 fused with the skull, not suspended ; and some of them exhibited 

 both these features. Their few survivors at the present day (the 

 Crossopterygians and Dipnoans) have also an air-bladder, which 

 might readily become a lung. The characteristic fish-fauna of the 

 Devonian period therefore made a nearer approach to the land 

 animals than any group of fishes of later date ; and it is noteworthy 

 that in the Lower Carboniferous of Scotland — perhaps even in the 

 Upper Devonian of North America, if footprints can be trusted — 

 amphibians first appeared. In Upper Carboniferous times they 

 became firmly established, and between that period and the Trias 

 they seem to have spread all over the world; their remains having 

 been found, indeed, in Europe, Spitzbergen, India, South Africa, 

 North and South America, and Australia. 



The Stegocephala or Labyrinthodonts, as these primitive amphibians 

 are termed, were therefore a vigorous race ; but the marsh-dwelling 

 habits of the majority did not allow of much variation from the 

 salamander pattern. Only in Upper Carboniferous and Lower Permian 

 times did some of their smaller representatives (the Microsauria) 

 become lizard-like, or even snake-like in form and habit ; and then 

 there suddenly arose the true reptiles. Still, these reptiles did not 

 immediately replace the Stegocephala in the economy of nature ; 

 they I'emained quite secondary in importance at least until the 

 Upper Permian, in most parts even until the dawn of the Triassic 

 period. Then they began their flourishing career. 



At this time the reptiles rapidly diverged in two directions. Some 

 of them were almost exactly like the little Sphenodon, which still 

 survives in some islands off New Zealand, only retaining more traces 

 of their marsh -dwelling ancestors. The majority (the Anomodonts 

 or Theromorphs) very quickly became so closely similar to the 

 mammals that they can only be interpreted as indicating an intense 

 struggle towards the attainment of the higher warm-blooded grade ; 

 and there is not much doubt that true mammals actually arose 

 about the end of the Triassic period. Here again, however, the 

 new race did not immediately replace the old, or exterminate it 

 by unequal competition. Eeptiles held their own on all lands 

 throughout the Jurassic and Cretaceous periods, and it was not until 

 the Tertiary that mammals began to predominate. 



