90 
SILURIA. 
[Chap. V. 
ridge of Caer Caradoc, might well account for all such partial dislocations ; 
and as the uppermost of the shelly sandstones at Cheney Longville clearly 
dipped under the Pentamerus zone or Hollies limestone (Upper Llandovery 
rock), and this last passed under the Wenlock shale, the general order of 
superposition, notwithstanding the adjacent disturbances, could not be 
doubted. See the preceding general woodcut, page 64. 
The fossils which most characterize this member of the deposit in Shrop- 
shire, as elsewhere, are Pentameri, particularly P. oblongus and P. lens, 
with Atrypa heniisphasrica, Bhynchonella decemplicata, and Strophomcna 
compressa. With these, however, there are other species, some of which 
occur in the Lower and many others in the Upper Silurian rocks. Among 
1. Pentamerus lens. 2. P. oblongus. 3. P. liratus, Sow. 4. Atrypa hemisphserica. 
5. A. reticularis. 6. Pentamerus undatus. 7. Strophomena compressa. 8. Holopella 
cancellata. 9. Bellerophon trilobatus. 10. Encrinurus punctatus. 11. Petraia subdu- 
plicata, M'Coy. 
the former are some of the species already enumerated, viz. Leptama seri- 
cea, Orthis calligramma, 0. biforata, Cyclonema crebristria, and all the 
species above mentioned (p. 87) which range from the Lower into the 
Upper Silurian rocks. The species common to this zone and the overlying 
formations are Phacops Stokesii, Atrypa reticularis, Pterinea retroflexa, 
Bellerophon trilobatus, B. expansus, and others. 
The woodcut, Foss. 15, exhibits those fossils only which are truly typical 
of the Llandovery rocks. Some of these forms, however, are so abundant 
in the Lower Silurian as well as in this zone, and so rare in the Wenlock 
formation or base of the Upper Silurian, that they still give a distinct 
impress to the deposit. 
In Shropshire, this zone of Pentamerus rock varies much in dimensions. 
When followed to the N.E. from the banks of the Onny, where it is a thin 
calcareous course only, it so swells out in the parishes of Church Preen and 
Kenley, that a considerable thickness of sandstone and conglomerate is 
there interposed between the shelly sandstone of Caer Caradoc and this 
Upper Llandovery limestone. Both those villages, as described in the 
1 Silurian System,' stand upon coarse grits with white quartz pebbles, in 
Upper Llandovery Fossils (15). 
