UPPER ORDOVICIAN BRACHIOPODS FROM KAZAKHSTAN 



63 



confirm from our sections (Fig. 14). In general shell shape and 

 fascicostellate radial ornament the Anderken material is similar to 

 Ranorthis Opik (1939) from the Volkhov and Kunda Stages of 

 Baltica. However, the generic attribution of deve.xa is tentative and it 

 may represent an undescribed genus. 



Family RANORTHIDAE Havlfcek, 1949 

 Genus EODALMANELLA Havlfcek, 1950 



TYPE SPECIES. Orthis socialis Barrande, 1879; from the Sarka 

 Formation (Llanvirn) of Bohemia. 



Eodalmanella extera Popov, 1985 PI. 12, figs 10-12, 15 



1985 Eodalmanella extera Popov: 54, pi. 1, figs 3-8. 



HOLOTYPE. CNIGR 4/11989, ventral internal mould (L=4.1. 

 W=6.1), from the Anderken Formation, Anderkenyn-Akchoku sec- 

 tion, Sample 843. 



Material. Five pairs of conjoined valves, 42 ventral and 48 dorsal 

 valves, internal and external moulds, from Samples 100b, 620 (BC 

 57189), 843, Anderkenyn-Akchoku section; Sample 1018, 7 km 

 southwest of Karpkuduk well, Kotnak Mountains. 



DESCRIPTION. Shell ventribiconvex, transverse, subrectangular in 

 outline, about 85% as wide as long with maximum width at mid- 

 length. Anterior commissure gently sulcate. Ventral profile 

 moderately convex, about one-third as thick as long, with maxi- 

 mum thickness at about one-quarter valve length. Dorsal valve 

 gently convex in transverse profile with maximum thickness 

 slightly anterior to the umbo and with shallow median sulcus 

 originating in the umbonal area. Dorsal interarea linear, strongly 

 anacline. Radial ornament multicostellate with 3-6 ribs per mm 

 along the anterior margin of mature specimens. Concentric orna- 

 ment of very fine ridge-like, evenly spaced fila, often branching 

 anteriorly. 



Ventral interior with teeth supported by short, divergent dental 

 plates and rounded subtriangular, slightly elongate muscle field 

 about 37% as long as the valve. Ventral adductor scars narrow, 

 subtriangular, slightly shorter than diductor scars. Cardinal process 

 ridge-like with bilobed, crenulated miophore. Brachiophores high, 

 triangular, with widely diverging bases. Fulcral plates well devel- 

 oped. Dorsal adductor scars quadripartite, extending anteriorly to 

 mid-valve, bordered laterally by low ridges. 



DISCUSSION. This species strongly resembles Scaphorthis? aulacis 

 Percival (1979a) from the Caradoc Goonumbla Volcanics of New 

 South Wales in the impunctate shell, radial ornament and internal 

 morphology of both valves. The Kazakh species differs in having 

 longer dental plates, a cardinal process with a long shaft crossing all 

 the bottom of the notothyrial cavity and well defined lateral ridges 

 bordering the dorsal adductor field. A detailed discussion and basic 

 statistics of this species were provided by Popov (in Nikitin & Popov 

 1985). 



Table 22 Measurements of dorsal valves of Pionodema opima sp. nov., Sample 8228 from Kopalysai Section, sample 8229 from Buldukbai-Akehoku and 

 Sample 7613 from Kujandysai section. 



Family CREMNORTHIDAE Williams, 1963 

 Genus PHRAGMORTHIS Cooper, 1956 



Type species. Phragmorthis buttsi Cooper, 1 956, from the Effna- 

 Rich Valley Formations (Llandeilo-Lower Caradoc) of Virginia, 

 U.S.A. 



Phragmorthis conciliata Popov, 1985 



PI. 1 1, figs 38^14; PI. 12, figs 1-9 



1985 Phragmorthis conciliata Popov: 52, pi. 1, figs 9-12. 



HOLOTYPE. CNIGR 10/11989 (PI. 12, figs 1, 2), dorsal valve 

 internal mould (L=4.5, W=7.2), from the Anderken Formation, 7 km 

 south-west of Karpkuduk well, Kotnak Mountains, Sample 1018. 



Material. Two pairs of conjoined valves, 6 ventral and 8 dorsal 

 valves, internal and external moulds, from Samples 626 (BC 57537), 

 8223a, Anderkenyn-Akchoku section; Samples 2538 (BC 57536), 

 7613 (BC 57535), Kujandysai section; Sample 8230, Buldukbai- 

 Akehoku section; Sample 1018,7 km southwest of Karpkuduk well 

 Kotnak Mountains; Sample 1024b, south side of Karatal River, south 

 of Sorbulak spring. 



Diagnosis. Shell ventribiconvex, transverse, subrectangular out- 

 line about 77% as wide as long with maximum width at mid-length, 

 anterior commissure gently unisulcate; ventral valve strongly con- 

 vex with maximum thickness between the umbo and mid-valve; 

 ventral interarea high triangular, apsacline with narrow open 

 delthyrium; dorsal valve moderately and evenly convex with narrow 

 and shallow sulcus originating at the umbo; radial ornament finely 

 and equally multicostellate with 5 ribs per mm along the anterior 

 margin of mature specimens. Ventral interior with elongate 

 subtriangular muscle field on pseudospondylium 2 1-26% as long as 

 the valve. Dorsal interior with simple, ridge-like cardinal process on 

 the high notothyrial platform which is strongly raised anteriorly; 

 high, blade-like median septum 88% valve length; large, deeply 

 impressed adductor scars, radially arranged, about 66% valve length. 



DISCUSSION. This species differs from Phragmorthis buttsi Cooper 

 ( 1956: 510) in its transverse subrectangular outline and lesser con- 

 vexity of both valves. It is on average about half the size of 

 Phragmorthis crassa Cooper (1956: 511) and has finer radial orna- 

 ment. Both P. buttsi and P. crassa have a subcarinate ventral valve, 

 which is another difference from the Kazakh species. 



Table 21 Measurements of ventral valves of Pionodema opima sp. nov.. 

 Sample 8228 from Kopalysai Section, sample 8230 from Buldukbai- 

 Akehoku and Sample 7613 from Kujandysai section. 





Lv 



W 



Ml 



Mw 



Lv/W 



Ml/L 



Iw/W 



N 



9 



9 



5 



6 



9 



5 



5 



X 



7.6 



9.4 



3.2 



3.5 



81.2% 



38.5% 



90.5% 



S 



1.38 



2.16 



0.63 



1.26 



8.6 



4.9 



14.9 



MIN 



5.0 



7.3 



2.6 



2.3 



68.5% 



34.2% 



64.9% 



MAX 



9.8 



13.8 



4.1 



5.7 



93.2% 



46.6% 



103.6% 





Ld 



W 



BB1 



BBw 



Ml 



Mw 



Lv/W 



Ml/L 



BBw/W 



N 



7 



7 



5 



5 



3 



3 



4 



3 



5 



X 



7.6 



9.5 



1.6 



2.6 



3.4 



3.1 



82.8% 



41.2% 



60.4% 



S 



2.36 



2.86 



0.15 



0.34 



0.32 



0.10 



10.7 



2.9 



9.9 



MIN 



3.2 



4.0 



1.4 



2.3 



3.2 



3.0 



70.1% 



38.8% 



50.0% 



MAX 



10.5 



12.9 



1.7 



3.1 



3.8 



3.2 



96.1% 



44.4% 



73.9% 



