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Ulrichostylus

Classification

    Phylum:  
Bryozoa
    Subphylum:  
Ectoprocta
    Class:  
Gymnolaemata
    Order:  
Cryptostomata
    Suborder:  
Rhabdomesina
    Family:  
Arthrostylidae
    Formal Genus Name and Reference:  
Ulrichostylus BASSLER, 1952, p. 384
    Type Species:  
Helopora divaricatus ULRICH, 1886a, p. 59, OD, ?Decorah Sh., equals Trenton shales of Ulrich, M. Ord., Minneapolis, Minn., USA


Images

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Fig. 281,1a-f. *U. divaricatus (ULRICH), syntypes (a, Univ. Minnesota 5928A; b-f, 5928B); a, apertural arrangement, longitudinal ridges; X11; b.c, zooecial cross sections and arrangements, linear axes; transv. peels, X70; d, radiating dark zones; transv. sec., X94; e, zooecial shapes; long. sec., X85; f, apertural outlines, longitudinal ridges; tang. sec., X85.-FiG. 281, 8,b. U. spiniformis (ULRICH), Lebanon Ls., M. Ord., Tenn., USA, all USNM 240853, X70; 8, apertural outlines, longitudinal ridges; tang. sec.; h, zooecial outlines, lamellar profile; long. sec.


Synonyms



Geographic Distribution

E.N.Am., Baltic region


Age Range

    Beginning Stage in Treatise Usage:  
M.Ord., ?U.Ord. (Chazy.-Blackriv.Richmond.)
    Beginning International Stage:  
Dapingian
    Fraction Up In Beginning Stage:  
0
    Beginning Date:  
471.26
    Ending Stage in Treatise Usage:  
M.Ord., ?U.Ord. (Chazy.-Blackriv.Richmond.)
    Ending International Stage:  
Katian
    Fraction Up In Ending Stage:  
100
    Ending Date:  
445.21


Description

Zoarium dendroid in some species, possibly unbranched in others. ] ointed longitudinally, also laterally in dendroid branches; joint surfaces generally weakly concave-convex; ball-and-socket pattern present in at least one species. Segments srraight or curved; diameters 0.5 to 1.0 mm, usually conStant between joints; cross sections polygonal to subcircular. Apertures in 6 to 8 longitudinal rows. Prominent longitudinal ridges separating apertural rows; apertures bordered proximally and laterally by sttong ridges that flare distally to join longitudinal ridges, forming inverted V-pattern. Ridges proximal to apertures sloping gradually into aperture below; 1 or 2 longitudinal ridges may be present on sloping surface. Metapores absent. Axial region formed by well-defined linear axis. Zooecial bases attenuated to weakly inflated. Zooecial cross sections triangular in endozone. Zooecial divergence from axis approximately 20 0 ro 40 ; 0 zooecial bend weakly developed, broadly rounded. Living chambers in exozone elliptical in cross section, oriented from 600 to 70 0 to branch surface. Zooeciallength 5 co 12 times diameter. Longitudinal arrangement of zooecia regular. Diaphragms scattered in elongate zooecia. Exozonal width more than half branch radius. Zooecial boundaries generally narrow in endozone, irregular, commonly with granular or nonlaminated material, locally not visible; well developed in exozone near proximal and lateral margins of chambers, positions obscure distal to chambers. Planar longitudinal dark zones radiating through exozone from near zooecial boundaries at base of exozone; appearance similat co that of zooecial boundaries. Lamellar profile in exozone rounded in transverse section, interrupted by radiating boundary zones; flattened in longitudinal section, sloping toward zoarially proximal zooecium. Exozonal wall material well developed. Paurostyles scattered, weakly developed, concentrated in wall between longitudinally successive zooecial chambers. [Ulrichostylus is distinguished on budding pattern, zooecial shape and orientation, and wall structure.]




References

Bassler, R. S., ,, ,, ,, , 1952, Taxonomic notes on genera of fossil and recent Bryozoa: J. Wash. Acad. Sci., v. 42, p. 381-385, 27 text-fig.


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