Vol. 62.] HIGHEST SILURIAN ROCES OF THE LUDLOW DISTRICT. 203 



The characteristic fossil of these Upper Whitcliffe Flags is pre- 

 eminently Chonetes striatella, which literally swarms in them. 

 Orbiculoidea rugata and OrtJioceras bullatum are also abundant ; but 

 Rhynchonella nucula and Orthis lunata, so common in the Lower 

 Whitcliffe Flags, are rare. 



The ' Ludford-Lane ' section, which is about 72 yards in length, 

 shows the passage between the Upper Whitcliffe Flags and the 

 Downton-Castle Sandstones. These beds are exposed in a high bank, 

 which has a maximum elevation of 12 feet. The general succession 

 is clearest on the northern side, where the beds can be seen dipping 

 south-eastward at 10° (cf. vertical section, fig. 1 below). 



The lowest beds seen are the Spirifera-elevata shales (D b) ; only 

 4 feet are, however, exposed, consisting of calcareous shales with 

 sandy beds, which contain Sp. elevata mut., Pterinea retrqflexa, and 



Pterygotus proble- 



Fig. 1. — Vertical section of the succession at 

 Ludford Lane ( Whitcliffe Road), on the scale 

 of 6 feet to the inch. 



if 



A 



Ec< 



E6< 



Ea< 



( De<l 





maticus. They are 

 immediately suc- 

 ceeded by the fa- 

 mous Ludlow Bone- 

 Bed (D c), which is 

 too well-known to 

 require description. 

 It is best developed 

 at the lower end 

 of the section, on 

 the south side of 

 the road, where it 

 is 2| feet above 

 road - level, and 

 reaches a maxi- 

 mum thickness of 

 nearly 6 inches. 

 It is, however, very 

 commonly separa- 

 ted into two thin 

 bands of ' bony ' 

 material, divided by a few inches of soft mudstone. These bands 

 occur in a more or less lenticular manner, and one or the other 

 disappears almost entirely from time to time, even within the short 

 distance occupied by the section. This feature is characteristic of 

 all the bone-beds of these highest Silurian rocks. In addition to the 

 numerous fish-remains and crustacean remains which the Bone- 

 Bed contains, we have identified Chonetes striatella, Orbiculoidea 

 rugata, and Orthis sp.: a similar fauna, with Beyrichia in addition, 

 being found in the softer mudstone separating the ' bony layers.' 



Temeside Group. — The succeeding sandstones (E a) differ some- 

 what in lithology from the beds described above ; they are mottled, 

 yellow, slightly-micaceous sandstones, with few traces of life. They 

 seem to usher in new conditions; for, above the Ludlow Bone-Bed, 





Bb 



Massive yellow micaceous sandstones 

 with Eurypterid-remains, Pachytheca, 

 and Lingula minima. 



~Beyrichia-Band. 



-3eyrichia-I$&Ti(l. 



-Beyrichia-B&nd. 



Argillaceous bed with PlatyscMsma 

 ~Beyrichia-Ba,n&. JThelioitesSc Modiol- 

 \_opsis comphxnata. 

 Mottled sandstones 

 and shales. 



Ludlow Bone-Bed. 

 Sandstone. 



Shale with Spirifera elevata mut. and 

 [Pterinea retroflexa. 



Shales and sandstones with 

 Spirifera elevata, Chonetes 

 striatella, Orbiculoidea rugata, 

 and Eurypteridae. 



