. Bulletins of American paleontology. Oldest Crinoids: Guensburg and Sprinkle 25. Key â¡ Fixed brachials â Radials V Infrabasals Text-rigure 13.âHabrotecrinus ibexensis n. gen. and sp., holotype PE 52740, plate tracing (solid lines) and reconstructed (dashed) ray- interray area (see PI. 8), secondary interbrachials, sutural pores not indicated, plating in proximal interbrachial area and in triangular space between radials and infrabasals uncertain, approximately ally only near cup base, two accessory plates in narrow crescentic gap away from cup base, two RR laterally above; larger dista
. Bulletins of American paleontology. Oldest Crinoids: Guensburg and Sprinkle 25. Key â¡ Fixed brachials â Radials V Infrabasals Text-rigure 13.âHabrotecrinus ibexensis n. gen. and sp., holotype PE 52740, plate tracing (solid lines) and reconstructed (dashed) ray- interray area (see PI. 8), secondary interbrachials, sutural pores not indicated, plating in proximal interbrachial area and in triangular space between radials and infrabasals uncertain, approximately ally only near cup base, two accessory plates in narrow crescentic gap away from cup base, two RR laterally above; larger distal accessory plate of this lowest gap also contacting R medially above; ?five RR (two pre- served), slightly taller than wide, 1 1 or 12 sided, lat- erally attenuated resulting in very narrow R-R suture, each R with ray ridges forming X shape, adjacent R pairs and B frame large triangular gaps below inter- brachial fields, gaps occupied by ?one or two inter- calate plate(s); large interbrachial areas each with many primaries and small secondary intercalate plates bearing rounded bosses, merging distally into tegmen; four I Bit, three in cup, large, shorter fourth armlike, axillary, rays branching near cup top, coarse rugose ornament extending up arms; 5-6 IIBrr. Illbrr more than eight, plate webs between IIBrr and IIIBrr branch- es; stem wide, pentalobate, pentameric. lateral mere boundaries at lobe crests, lumen pentalobate, large. Occurrence.âTime slice 2c, trilobite biozone J, basal Wah Wah Formation, uppermost Ibexian. middle Arenig. uppermost Lower Ordovician (see Appendix). Type material.âThe single specimen is holotype PE 52740. Etymology.âIbexensis. in reference to Ibex Well. the source of water near the collecting locality. Discussion.âSee genus Discussion. SYSTEMATIC POSITION UNCERTAIN Stem A Plate 9. figures 3, 4 Discussion.âThese stem segments are pentameric and originally pentalobate in cross section. The larger flattened specimen is 1 cm wide, cm long
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