ORDOVICIAN BRACHIOPODA 149 



(Grid Ref. SO 279997) ; BB 35453 from exposures half-way down the path going 

 southwards below Marrington Farm (Grid Ref. SO 272967). 



Discussion. The few impressions of Leptaena found in the Whittery and Hagley 

 Shales compare very closely with those of L. ventricosa Williams (1963 : 462) from the 

 Gelli-grin Group of the Bala district. The disc of L. ventricosa s.s., which is about 

 three-fifths as long as wide, as well as the ventral muscle scar, may prove to be 

 consistently longer ; but provisionally the Shropshire material is reasonably identi- 

 fied as conspecific with the Welsh. 



KIAEROMENA Spjeldnaes 1957 



Kiaeromena cf. kjerulfl (Holtedahl) 



(PI. 27, figs. 6, 10, 11) 



1916 Leptaena kjerulfi Holtedahl : 72. 



1957 Kiaeromena kjerulfi (Holtedahl) Spjeldnaes : 183. 



1963 Kiaeromena cf. kjerulfi (Holtedahl) Williams : 464. 



Diagnosis. Obtusely geniculate Kiaeromena with a disc about 12 mm long, 

 ornamented by up to 9 coarse concentric rugae and unequally developed parvicostel- 

 lae numbering about 6 per mm, 10 mm antero-medially of the ventral umbo ; 

 subcircular ventral muscle field about 6 mm long. 



Description. Subquadrate Kiaeromena with a rounded obtuse angle of genicula- 

 tion to define a plano-convex disc about 12 mm long and almost twice as wide 

 ornamented by up to 9 coarse concentric asymmetric rugae with wavelengths of 

 1-5 mm and steeper posterior slopes ; radial ornamentation unequally parvicostellate 

 especially on the trail with a count of 6 per mm, 10 mm antero-medially of the ventral 

 umbo ; ventral and shorter dorsal interareas apsacline and anacline respectively 

 with the pseudodeltidium and beak pierced by a large supra-apical foramen, and an 

 arched chilidium. 



Ventral interior with trigonal teeth supported by divergent dental plates acting 

 as the posterior boundaries of a poorly preserved subcircular muscle scar extending 

 forward for about 6 mm. 



Dorsal interior with a cardinal process consisting of a small median ridge flanked 

 by two acutely divergent lobes and poorly defined socket ridges supported by a 

 massive, anchor-shaped notothyrial platform. 



Figured material. 



length width (mm) 

 Incomplete external and internal moulds of pedicle valve 

 (BB 35406a, b) 25 



Incomplete external and internal moulds of brachial valve 

 (BB 37132a, b) - - 



Horizons and localities. BB 35406 from Whittery Shales exposed in the lower 

 part of the west bank of the River Camlad, 60 yds north-east of Marrington Farm 

 (Grid Ref. SO 272970) ; BB 37132 from Hagley Volcanics exposed in a roadside 

 quarry 150 yds north of Church Stoke Hall (Grid Ref. SO 274942). 



