go SHELVE DISTRICT 



Cardinal process consisting of linear shaft and small rounded myophore ; brachio- 

 phores short divergent, with subparallel bases flanking well-developed notothyrial 

 platform extending anteriorly for 22% of the length of the brachial valve and sep- 

 arated from each other by 97% of their length ; adductor scars poorly differentiated, 

 suboval, situated on either side of low median ridge and extending anteriorly for 

 59% of the length of the brachial valve. 



Figured material. 



length width (mm) 

 Internal mould of brachial valve (BB 35434) 4-0 



Internal mould of pedicle valve (BB 35435) 3-5 - 



Internal mould of brachial valve (BB 35436) 3-0 



External mould of brachial valve (BB 35437) 4-0 - 



Horizon and locality. Lower Llandeilo yellow-weathering calcareous sand- 

 stones exposed in quarry 300 yds west of Ysgubor-wen Farm, Llandeilo (Grid Ref. 

 SN 644224). 



Dalmanella salopiensis sp. nov. 

 (PL 15, figs. 5, 6, 8-12) 



Diagnosis. Small, ventribiconvex Dalmanella with a brachial valve JJ°/ as 

 long as wide and 15% as deep as long and fine costellae, rarely branching externally, 

 commonly numbering 6 per mm at the 2 mm growth stage ; dental plates 21% as 

 long as the pedicle valve and 159% as divergent as long ; ventral muscle scar extend- 

 ing anteriorly for 35% of the length of the pedicle valve ; subparallel brachiophore 

 bases 22% as long as the brachial valve and separated from each other by 86% of 

 their length. 



Description. Small, subquadrate, ventribiconvex Dalmanella with obtuse 

 cardinal angles ; pedicle valve 38% as deep as long with rounded carina medially 

 and evenly sloping lateral areas, brachial valve 77% as long as wide and 15% as 

 deep as long with shallow median sulcus about four-fifths as wide as valve length 

 flanked by evenly convex lateral areas ; ventral interarea slightly curved apsacline, 

 longer than anacline dorsal interarea, delthyrium and notothyrium open ; radial 

 ornamentation of costellae commonly 6 per mm 2 mm antero-medially of the dorsal 

 umbo ; branching simple, rarely developing externally with only 4 external ribs 

 observed in 32 mature brachial valves. 



Teeth supported by dental plates extending anteriorly for 21% the length of the 

 pedicle valve and extending laterally to 159% of their length ; ventral muscle scar 

 bilobed extending anteriorly for 35% of the length of the pedicle valve ; mantle 

 canal system unknown. 



Cardinal process consisting of linear shaft and compact myophore on a well- 

 developed notothyrial platform ; brachiophores short, divergent with subparallel 

 bases extending anteriorly for 22% of the length of the brachial valve and separated 



