88 BRITISH FOSSILS. 



Of the terminal palette we have no trace ; its probable shape is 

 given in the dotted outline. 



Only the metastoma, fig. 13, remains to be described. It is 

 greatly like that of P. anglicus, Plate VI., and chiefly differs in the 

 more contracted base, and large open plicae of the surface. The 

 notch is somewhat deeper. It may have been smooth over the 

 hinder portion, as in Plate XII. fig. 3, which is the same or a closely 

 allied species, and may be noticed here, though possibly it belongs to 

 P. ludensis, above described. 



Plate XII. fig. 3. This post-oral plate, in its anterior portion, a 

 good deal resembles that figured in Plate IX., the notch being a little 

 less deep only. The shape is much more elongate than in P. anglicus, 

 the length being as seven to four ; the width is greatest at the anterior 

 third, and the general shape ovate. The plicae are large and open, 

 and are confined to the anterior portion about the notch. 



The basal joint of the swimming foot (fig. 6), found at the same 

 locality, is in almost every resp.ect like that of P. gigas, having 

 the teeth broad and short. 



Locality. Downton Sandstone (UPPERMOST LUDLOW Rock) of 

 Kington, Herefordshire. (Cabinet of Mr. R. Banks, of that place.) 

 Some specimens, presented by that gentleman, are in the Museum 

 of Practical Geology. Plate XII. figs. 3, 6 are also specimens in the 

 Museum, collected by Mr. A. Marston, of Ludlow. They were found 

 at the Ludlow Railway Bridge, in the passage beds at the base of 

 the Old Red Sandstone. 



