VII. 



FISHES OF THE OLD RED. 



79 



Devonian group. The old red sandstone is followed in Devon- 

 shire, and still more remarkably in the south of Ireland, by a 

 series of shales, grits, and limestones, with a large suite of fossils, 

 having on the whole a considerable analogy with the still richer 



Diagram XIX. 



I. Pteraspis (Scaphaspis) Lloydii. The external surface is retained. 2. Another, 

 a cast of the interior. 3. The three plates of which the dermal covering is 



formed. The outer one is striated enamel ; the middle one shews vertical cells of 

 various forms ; the inner one is in thin bluish scales. 4. Cephalaspis. Only 



one of the cornua is seen. 



The specimens are from Mathon, near Malvern, in cornstone and sandstone of the 

 old red series. 



associations of marine life in the carboniferous limestone. In North 

 and South Devon, in the Eifel, and about the junction of the Rhine 

 and the Lahn, these strata are thick and various. A series cor- 

 responding to them occurs in North America, but in none of these 

 localities, except in Ireland and Devon, is there a distinct exhibition 

 of old red sandstone. And in these districts the exhibition can 

 hardly be termed normal/ Near Linton, in North Devon, and 

 south of Plymouth we may satisfy ourselves of the fact that old 

 red sandstone underlies the Devonian beds. In North Devon these 

 strata of great thickness comprise one limestone of age corresponding 

 to the Eifel rock, several grey shaly rocks full of fossils, and some 

 purple grits and shales without fossils. Slaty cleavage affects a large 

 portion of the lower rocks. From this series of rocks to the car- 

 boniferous strata which succeed, the transition is easy, so easy 

 indeed that, in the opinion of Sir R. Griffith and Mr. Jukes, the 

 whole of the Devonian series may be united with the lowest members 



