CAMBRIAN- ROCKS IN SOUTH SHROPSHIRE. 663 



the north-west by a fault which divides it from rocks similar to 

 those of the Wrekra. The quartzite, which in the Wrekin district 

 intervenes between the sandstone and the central rocks of the axis, 

 is here absent. I have not detected fossils in this area. 



Physical Features oe the Shtneton Area. 



The Shineton Shales, as may be imagined from their uniform soft- 

 ness, present few striking inequalities in the landscape ; but to the 

 north of the Severn, where small streams have cut deeply into them, 

 the narrow and picturesque ravines called respectively Back Dingle 

 and Mary Dingle are formed. To the south-west of the Wrekin. 

 the Holly bush Sandstone constitutes high ground sloping down 

 towards the shales ; but to the north-east of the area, where the 

 AVrekin chain rises into a lower elevation called the Ercal, the sand- 

 stone forms a distinct wooded ridge parallel to the axial elevation of 

 the district, and during the north-easterly part of its course is 

 accompanied by a second parallel ridge, caused, I believe, by a repe- 

 tition by a fault. In the disturbed region on Cound Brook, the 

 outliers of Caradoc sandstone give great variety to the scenery, 

 forming the cappings of low but steep hills separated by narrow 

 gorges excavated in the soft Harnage Shales. The Hoar-Edge Grits 

 also constitute the low ridge on which Acton Pigott is situated. 

 The same sandstone, with the upper arenaceous beds of the Shineton 

 Shales underlying, forms the ridge which limits the area of the 

 Shineton Shales to the south-west, and rises to a bold elevation at 

 Shadewell Coppice, overhanging Acton-Burnell Park. In this same 

 locality the Chatwall Sandstone, partly covered in by the May-Hill 

 Sandstone, makes a ridge running roughly parallel to the Hoar-Edge 

 Grits, the intermediate Harnage Shales being hollowed out into a 

 deep valley. 



DESCRIPTION OF THE FAUNA. 



Asaphus, Brongn. 



Asaphellus, nov. subgen. 



Asaphus (Asaphellus) Homfrayi, Salter. (Plate XXIV. fig. 1.) 



Our Shineton form is undistinguishable from Salter's species. I 

 reproduce part of his description (Mon. Sil. Tril. p. 165, pi. xxiv. 

 figs. 6-12) :— 



" The head is more than a third of the whole length, and longer 

 than the thorax, which in its turn is longer than the caudal shield. 

 The head is semioval, rather pointed in front, and has very short 

 posterior spines ; it is broadly depressed round the margin. The 

 glabellar portion is scarcely marked out ; the eyes are placed nearly 

 halfway up the head ; they are small (two lines long), the facial 

 sutures curving out boldly beneath them, and cutting the posterior 

 margin more than halfway out from the axis. Above the eye they 

 form a narrow ogive, and nearlv follow the front margin. On the 



2x 2 



