ORDOVICIAN BRACHIOPODA 



81 



cardinal process 

 socket 

 — tooth 



brachiophore 



dental plate 



muscle scar 



Fig. 7. Diagrammatic views of (A) the ventral and (B) the dorsal interiors of 



Salacorthis. 



Ventral interior with subparallel dental plates extending forward for one-seventh 

 the pedicle valve length, suboval ventral muscle scar undifferentiated, extending 

 anteriorly for nearly one-third the length of the pedicle valve. 



Dorsal interior with brachiophore bases extending forward for over one-quarter 

 the length of the brachial valve ; median septum supporting the cardinalia short, 

 extending anteriorly for two-fifths the length of the brachial valve. 



Type material. 



Holotype 



length width (mm) 



Paratypes 



37 

 ii-o 



5-o 



12-0 



4-5 



External and internal moulds of brachial valve 



(BB 37153a, b) 



Internal mould of pedicle valve (BB 37154) 



Incomplete external mould of brachial valve 



(BB 37155) 



Incomplete external mould of brachial valve 



(BB 37156) 



Incomplete external mould of brachial valve 



(BB 37157) 



Horizon and localities. Spy Wood Grit : BB 37153, 37154 from exposures on 

 top of ridge 1440 yds NNE of Rorrington bench mark 599 (Grid Ref. SJ 303018) ; 

 BB 37155, 37157 from outcrops 1100 yds NNE of Rorrington (Grid Ref. SJ 303015) ; 

 BB 37156 from outcrops in the north bank of Spy Wood Brook 170 yds north-east 

 of Spy Wood Cottage (Grid Ref. SO 282958). 



Discussion. No other species congeneric with Salacorthis costellata has yet been 

 so described although in view of the strongly developed platystrophiinid characters 

 of the Spy Wood form and the microscopic nature of its chief differentiating feature, 

 some stocks, currently recorded as Platystrophia or Mcewanella, may ultimately 

 prove to belong to the genus. 



