ORDOVICIAN BRACHIOPODA 21 



composed of Palaeoglossa, Schmidtites and Schizocrania with the last genus alone 

 occurring in six extra localities and each of the first two in an additional five. 

 Immature shells of Rafinesquina are most widely distributed, followed by Dalmanella 

 and Glyptorthis. These presumably represent unsuccessful waves of colonization by 

 an association akin to those characteristic of the Meadowtown Beds and the succeed- 

 ing calcareous Spy Wood Grit (Table 8). The Spy Wood community is dominated 



Table 8 



The number of pedicle or brachial valves of the listed species recovered 

 from 7 localities of Spy Wood Grit 





i 



2 



3 



4 



5 



6 



7 



Bicuspina modesta 



- 



- 



4 



2 



i 



50 



12 



Bystromena perplexa 



i 



2 



2 



- 



i 



8 



7 



Dalmanella salopiensis gregaria 



- 



3 



7 



2 



i 



76 



25 



Drabovia cf . fascicostata 



i 



- 



i 



- 



- 



12 



- 



Glyptorthis viriosa 



i 



- 



i 



I 



i 



21 



4 



H arknessella cf . subplicata 















1 



Heterorthis sp. 



- 



- 



- 



- 



i 



10 



2 



Horderleyella cf . plicata 



- 



- 



- 



- 



- 



3 



1 



Kjaerina (Hedstroemina) sp. 



- 



- 



- 



- 



- 



1 



1 



Onniella sp. 



- 



- 



- 



I 



- 



- 



- 



Palaeoglossa attenuata 



i 



I 



- 



- 



- 



18 



4 



Parastrophinella musculosa 



- 



- 



- 



- 



- 



6 



2 



Paterula cf . perfecta 



- 



3 



- 



I 



- 



4 



- 



Platystrophia cf. major 



- 



- 



- 



- 



- 



1 



1 



Rostricellula sparsa 



- 



- 



- 



- 



- 



5 



- 



Salacorthis costellata 



- 



- 



i 



- 



- 



5 



2 



Salopia cf . salteri 



- 



- 



- 



- 



- 



2 



- 



Schizocrania salopiensis 



i 



- 



- 



I 



i 



13 



3 



Skenidioides cf. costatus 



- 



- 



4 



- 



- 



3 



- 



Sowerbyella multiseptata 



- 



i 





I 



- 



24 



11 



Zygospira sp. 



- 



- 



- 



- 



- 



1 



- 



by articulate brachiopods like Dalmanella, Glyptorthis, Bystromena, Bicuspina and 

 Sowerbyella, although Palaeoglossa and Schizocrania persist. 



The Aldress Shales, like many of the older formations, bear traces of two distinct 

 associations (Table 9). The more commonly occurring is typified by Paterula and 

 Schmidtites which have also been recovered from three and one extra localities 

 respectively, and is found in medium grey micaceous siltstones. Crystal tuffs, on 

 the other hand, supported a relatively prolific fauna dominated by Sowerbyella, 

 Dalmanella and Onniella. 



The fossil-bearing members of the two youngest Ordovician formations preserved 

 in the Shelve area, the Hagley and Whittery Shales, consist mainly of light olive- 

 grey calcareous tuffs and mudstones. However, the Whittery mudstones contain 

 lithic and crystal fragments of volcanic debris up to 1 cm in size, mud balls and 

 broken shells, which suggest that even those parts of the formation not obviously 

 derived from volcanic ash falls may have been deposited by lahars. Indeed the 

 only non-volcanic sediment appears to be a light olive-grey micaceous siltstone 



