THE OLDEST FOSSILS OF ALL 



have a very highly complex structure and red- 

 coloured blood. It is indeed a most remarkable 

 fact that the remote fossil shells of the lower 



Fig. 199. — Lingula {Lingulella) davisii, of the natiiral size, 

 embedded in the slaty rock of Port Madoc, North Wales. 



Cambrian strata should be identical with those of 

 a living animal of a high rank in the scale of 

 structure. Not only is that the case, but in all 



Fig. 200. — One of the most ancient Trilobites known (Cono- 

 coryphe lyellii), from the Lower Cambrian of Nun's Well, 

 Wales. From a drawing by Professor Gaudry. This 

 Trilobite is also called Conocephalites. 



the deposits above the Cambrian we find the 

 shells of Lingula, so that we must conclude 

 that Lingula has been existing in the seas of 



273 T 



