ii 4 SHELVE DISTRICT 



Table 85 



The distribution of brachial valves of Tissintia prototypa (Williams) from the Weston Beds (A) 

 and the Lower Llanvirn of Llandeilo (B), and of Tissintia immatura (Williams) from the Meadow- 

 town Beds (C), with 3-6 costellae per mm, 5mm antero-medially of the dorsal umbones 



costellae per mm 

 3 4 5 6 



A 1 4 11 o 



B 2 18 27 4 



C 12 6 1 o 



Family LINOPORELLIDAE Schuchert & Cooper 1931 



SALOPIA Williams 1955 



Salopia cf. salteri (Davidson) 



(PI. 19, figs. 10, 11) 



An incomplete mould of a brachial valve (BB 35426a, b) is the only record of 

 Salopia in Spy Wood Grit. The specimen, which was recovered from the outcrops 

 1 100 yds NNE of Rorrington (Grid Ref. SJ 303015), indicates that the convex and 

 gently sulcate valve was about 5 mm long and was ornamented by fine multicostellae 

 with a density of 6 per mm at the antero-medial margin. Although the mould is 

 broken posteriorly it is possible to determine that the cardinalia included a pair of 

 widely placed brachiophore bases bounding a low notothyrial platform supporting 

 the linear shaft of a cardinal process. The notothyrial platform passes anteriorly 

 into a broad median ridge with adductor impressions on either side. 



In respect of its preserved features, the valve is indistinguishable from that of 

 Salopia salteri (Davidson) as illustrated in Whittington & Williams (1955, pi. 38, 

 figs. 45, 46) and provisionally, at least, may be assigned to that species. 



Salopia sp. 

 (PI. 19, figs. 6-9) 



In contrast to the Spy Wood representative of Salopia, the three congeneric moulds 

 from the Whittery Shales, exposed in Whittery Quarry (BB 35428a, b, BB 35429a, b) 

 at the south end of Whittery Wood near Chirbury (Grid Ref. SO 275981) and in the 

 stream (BB 35430a, b) at the north end of Spring Coppice 865 yds south-east of 

 Hockleton Bridge (Grid Ref. SO 279997), are less decisively related to 5. salteri. The 

 two pedicle valves represented by the moulds BB 35429 and 35430 were strongly 

 convex, about one-quarter as deep as long, rectimarginate, with a high apsacline 

 interarea. The widely placed dental plates were more nearly parallel in the smaller 

 valve than the larger although the muscle fields of both, consisting of a pair of lobate 

 diductor scars flanking a narrow median adductor track, were impressed beyond the 

 limits of the dental plates and extended forwards for up to one-third the length of 

 the valve. The ribbing was too poorly preserved on external moulds to indicate 

 more than a finely costellate condition. However, costellae ornamenting the brachial 

 valve (BB 35428), although occurring with a density comparable with that of 



