NORTH STAFFORDSHIRE COAL FOSSILS. 223 



a considerable portion of the body. A short, strong spine, 

 marked with coarse longitudinal ridges, projects from the 

 dorsal surface. The body is covered with shagreen, dermal- 

 tubercles occurring in large patches on various portions of 

 the fish. The jaws are somewhat of the shape of a horse- 

 shoe. Three teeth, each of different forms, are arranged on 

 each side the jaw. -f- 



Position and locality : Hard mine coal shale, Adderley 

 Green ; Knowles ironstone, Fenton. 



Pleurodus affinis, Agassiz. (Ref., Poiss. Foss., vol. 



iii., p. 174.) Detached teeth, which we refer to this 



species, have been found in the same beds as the 



preceding species. Probably the two forms are not 

 specifically distinct. 



Position and locality : Hard mine coal shale, Adderley 

 Green ; Knowles ironstone, Fenton. 



GENUS PCECILODTJS, AGASSIZ. 



This genus is very rare in these coal-measures. The most 

 prominent characteristic of teeth of this genus is the longi- 

 tudinal step-like ridges which cross the surface of the tooth. 

 Two or three imperfect specimens of an unrecognized species 

 have been found at Longton. 



Position and locality : Roof of Bay coal, Longton. 



t Monthly Review of Dental Surgery, 1874. 



