NORTH STAFFORDSHIRE COAL FOSSILS. 227 



Position and locality : Cockshead ironstone, Adderley 

 Green ; Knowles ironstone, Fenton. 



GENUS PYGOPTERUS, AGASSIZ. (Ref., Poiss. Foss., vol. ii., 



p. 74.) 



Three distinct species of Pygopteri occur in the 

 Pottery coalfield. The most common species is one which 

 ranges from five inches to nearly two feet in length. The 

 scales are lozenge-shaped : the upper surface is ornamented 

 with well-defined ridges on the posterior margin ; the 

 anterior margin is minutely punctured. A full description 

 of the structure and peculiarities of these species will shortly 

 appear. 



Position and locality : Knowles and Deep mine iron- 

 stones, Fenton and Longton. 



FAMILY, SAURODIPTERINI, HUXLEY. 

 GENUS MEGALICHTHYS, AGASSIZ. 



Megalichthys Hibberti, Agassiz. (Ref., Poiss. Foss., vol. ii., 

 tab. 63 64.) This is one of the most abundant and 

 widely distributed of the fishes found in these coal-measures. 

 There are few fossiliferous beds that do not contain fragments 

 of this interesting fish. Although not rare, it generally 

 occurs in a fragmentary condition, only one or two nearly 

 entire specimens have been found. The average length of 

 Megalichthys is about five feet ; fragments which must have 

 belonged to fishes of this size have been collected in various 

 parts of the coalfield. The body of the fish is covered with 

 quadrangular scales (see plate, fig. 14), which cross the 

 body obliquely and over-lap each other. The posterior or 



