1 86 THE SUCCESSION OF ANIMAL FORMS 



spondylus of Traquair, may raise still higher hopes for the early 

 vertebrates. It is a little creature, an inch to two inches in 

 length, destitute or nearly destitute of bony covering, having a 

 head which suggests the presence of external gills, large eyes, 

 and even elongated nasal bones, 1 a long vertebral column 

 composed of separate bony rings, more than fifty in number, 

 with possible indications of ribs in front and distinct neural 

 and haemal processes behind. One cannot look at it with- 

 out the suggestion occurring of some of the smaller snake- 

 like Batrachians of the Carboniferous and Permian; and I 

 should not be surprised if it should come to be regarded 

 either as a forerunner of the Batrachians or as a primitive 

 tadpole. 



However this may be, the upper part of the Devonian, though 

 rich in fishes and plants, has afforded no higher vertebrates 

 than its lower parts, and in the lowest Carboniferous beds we 

 suddenly find ourselves in the presence of Batrachians with 

 well-developed limbs and characters which ally them to the 

 Lizards. True lizard-like reptiles appear in the Permian, and 

 then we enter on that marvellous reign of reptiles, in which 

 this class assumed so many great and remarkable forms, and 

 asserted itself in a manner of which the now degraded reptilian 

 class can afford no conception. 



The mammals and birds make their first appearance quietly 

 in small and humble forms in the reign of reptiles, in which 

 there was little place left for them by the latter ; but the 

 mammals burst upon us in all their number and magnitude in 

 the Eocene and Miocene, in which quadrupedal mammalian 

 life may be said to have culminated in grandeur, variety, and 

 geographical distribution ; far excelling in these respects the 

 time in which we live. 



The development in time of the back-boned animals thus 

 stands in some degree by itself; but it illustrates the same 

 1 I am aware that Woodward regards these parts differently. 



