ORDOVICIAN BRACHIOPODA 29 



both valves evenly convex in longitudinal and transverse profiles ; external surface 

 ornamented by concentrically disposed impersistent lamellae giving a finely scalloped 

 appearance ; ventral beak acute, dorsal beak obtusely rounded. 



Ventral pseudointerarea striated, slightly anacline to orthocline, crescentic in 

 outline and divided into 2 curved propareas by a shallow, relatively wide pedicle 

 groove extending forward for 9% of the valve length ; umbonal muscle scars suboval 

 located immediately anteriorly of the propareas ; 2 short, low ridges narrowly diverge 

 from the anterior end of the pedicle groove. 



Dorsal pseudointerarea striated, orthocline, lenticular in outline and extending 

 forward for 7% of the length of the brachial valve ; dorsal muscle impressions 

 unknown ; postero-medial internal surfaces of both valves sporadically and 

 shallowly pitted. 



Type material. 



length width (mm) 



Holotype Incomplete external and internal moulds of 



pedicle valve (BB 37144a, b) 14-0 11-5 



Paratypes External and internal moulds of pedicle valve 



(BB 37146a, b) 12-0 io-o 



External and internal moulds of brachial valve 



(BB 37147^, b) 15-0 ii-o 



External and internal moulds of pedicle valve 



(BB 37148a, b) 14-0 12-0 



Internal mould of brachial valve (BB 37149) 14-5 14-0 



Horizons and localities. Meadowtown Beds : BB 37144 from exposures 

 80 yds from Meadowtown Quarry along the Rorrington road (Grid Ref. SJ 311012) ; 

 BB 37146 from a small excavation in the corner of a field alongside the cart-track 

 from Meadowtown to Waitchley 330 yds due south of Waitchley (Grid Ref. 

 SJ 311017) ; BB 37147 from outcrops 570 yds south-west of Meadowtown Quarry 

 (Grid Ref. SJ 306009) ; BB 37148 from outcrops along the lane to Lower Ridge from 

 bench mark 754, Little Weston (Grid Ref. SO 293984) ; BB 37149 from Rorrington 

 Beds exposed in Lower Wood Brook 400 ft south-east of the Meadowtown -Rorring- 

 ton road (Grid Ref. SJ 307008). 



Lingulella displosa petila sp. et subsp. nov. 

 (PI. 2, figs. 9-11 ; PL 3, fig. 1) 



Diagnosis. Gently biconvex, suboval Lingulella with a brachial valve 70% as 

 wide as long, ornamented by impersistent concentrically arranged lamellae, pedicle 

 groove and dorsal pseudointerarea extending anteriorly for 13% and 8% of the valve 

 length respectively. 



Description. Subequally biconvex Lingulella normally suboval in outline with 

 well-rounded anterior margins and a maximum width at about 60% of the shell 

 length anterior of the umbones ; pedicle valve about 5% as deep as long and, on 

 average, 70% as wide as long (range 63% to 80% for 5 specimens), both valves 



