132 
deflected basal diaphragms, and are therefore mesozooecia (sensu 
stricto), but the term exilazooecia is retained for consistency with 
the genus description. 
Autozooecial wall thickness averages 0.05 mm in the exozone. 
Wall microstructure is composed of steeply inclined, V-shaped 
laminae; the zooecial wall boundaries are dark and granular. Some 
exilazooecia are infilled with laminar calcite close to the zoarial 
surface. In longitudinal section this infilling consists of broad U- 
shaped laminae. 
REMARKS. Halloporina crenulata, the type species of the genus, 
has been described from the Black River and Trenton Formations 
(middle Ordovician) of the U.S. mid-west but has not been recog- 
nised elsewhere. Only one other species of Halloporina has hitherto 
been identified: H. parva (Ulrich & Bassler, 1904), also from the 
Black River and Trenton Formations of the U.S. mid-west. H. 
crenulata is distinguished from H. parva in having a larger zoarium, 
larger rounded zooecial apertures (H. parva has polygonal zooecial 
apertures) and more abundant exilazooecia. Nothing is known about 
the range of variation within either species of Halloporina. Ulrich & 
Bassler (1904: pl. xiv) illustrated the two species. Colony size 
appears to be the only major difference between them as shown in 
the illustrations. The drawings indicate little difference in zooecial 
aperture shape; the tangential section of H. crenulata is, however, 
deeper than in H. parva. A re-examination of the species and further 
material, is needed for a greater understanding of these species. 
The specimens from Clog-y-fran are identified only as H. cf. 
crenulata. The identification is tentative due to the presence of 
occasional diaphragms within the outer exozone. The rounded 
zooecia and relatively abundant exilazooecia suggest similarity to 
H. crenulata rather than H. parva. 
Order CRYPTOSTOMATA Vine, 1884 
Suborder PTILODICTICTYINA Astrova & Morozova, 1956 
Family ESHAROPORIDAE Karklins, 1983 
Genus GRAPTODICTYA Ulrich, 1882 
Graptodictya bonnemai Bassler, 1911 Figs 28-29 
1911  Graptodictya bonnemai Bassler: 122, pl. 8, fig. 3, text-fig. 
48. 
1921  Graptodictya bonnemai jaervensis Bekker: 58, pl. 8, figs 
1. 
1952  Graptodictya bonnemai Bassler; Toots: 126, pl. 7, figs 5, 8, 
pl. 8, fig. 3, pl. 9, figs 1, 2, pl. 10, fig. 1. 
1965 Graptodictya bonnemai Bassler; Astrova: 2252, pl. Ix, fig. 2, 
pl. xi, fig. 1. 
1970 Graptodictya bonnemai Bassler; Nekhorosheva: 86, pl. vit, 
fig. 1. 
MATERIAL. NHM PD 8389-8391, 8392b, 9393. 
OTHER OCCURRENCES. kKuckers Shale (Kukruse Stage, Llandeilo), 
Baron Toll’s Estate, Estonia; Jarve, Kukersite Quarry, Wesenberg 
Limestone (Kukruse Stage, Llandeilo), Wesenberg, Estonia; Vaigach 
Island and Pai-khoi (Yugorskiy Stage, Llandeilo/Caradoc), Urals, 
Russia. 
DESCRIPTION. Zoaria erect with thin branches, on average 1.85 
mm wide by 0.69 mm deep. The margins of the branches are striated. 
Mesothecae are thin and sinuous. In the exozone the autozooecia 
form 90° angles with the mesothecae. Autozooecial apertures are 
oval in shallow tangential sections and average 0.48 mm by 0.3 mm 
C. BUTTLER 
in the exozone. Short superior hemisepta are commonly present. 
Autozooecial boundaries are slightly serrated. Zooecial wall micro- 
structure is composed of broadly U-shaped laminae. Exilazooecia 
and diaphragms are absent. 
REMARKS. Graptodictya bonnemai was first described by Bassler 
(1911: 122) from Estonia, as being very similar to the type species of 
Graptodictya (G. perelegans). The two species were distinguished 
by G. bonnemai branching less frequently and having more elongate 
autozooecial apertures. 
Order FENESTRATA Elias & Condra, 1957 
Suborder PHYLLOPORININA Lavrentjeva, 1979 
Family ENALLOPOROIDAE Miller, 1889 
Genus PUSHKINELLA Lavrentjeva, 1979 
Pushkinella sp. Fig. 30 
MATERIAL. NHM PD 8376-8378, 8380-8383. 
DESCRIPTION. Zoaria are reticulate and anastomosing; only frag- 
mentary specimens have been found at Clog-y-fran. No exterior 
frontal views of the colonies are available because frontal surfaces 
are all embedded in sediment. 
Fenestrules are oval-rounded, with diameters averaging 0.58 mm 
by 0.42 mm. Branches are rounded and average 0.38 mm diameter. 
The exozone 1s distinguished by a change in the orientation of the 
autozooecia and considerable thickening of the zooecial walls. 
Autozooecia are rounded in the endozone, becoming rounded- 
slightly petaloid in the exozone, where they average 0.16 mm in 
diameter. Across one branch one to three autozooecia are present. 
Wall microstructure is hard to distinguish. In one specimen (PD 
8378) longitudinal laminar microstructure can be identified. Short, 
narrow acanthostyles are abundant throughout the colony; in the 
exozone they occasionally indent the autozooecial apertures. The 
acanthostyles are composed of a hyaline core surrounded by conical 
laminae, and are on average 0.1 mm in diameter. 
REMARKS. The genus Pushkinella was previously known only 
from the Baltic region of the former Soviet Union. Two Ordovician 
species have been recognised: P. mirabilis Lavrentjeva 1979, and P. 
robusta Lavrentjeva 1979, from Estonia, and one Silurian, P. 
acanthroporoides Pushkin 1976, from Byelorussia. 
The Welsh specimens of Pushkinella are characterised by the 
anastomosing colony form, the small oval-rounded fenestrules and 
rounded branches. Autozooecial walls are extensively thickened in 
the exozone and autozooecial apertures are rounded to slightly 
petaloid. Short and narrow acanthostyles are abundant. 
The Welsh specimens differ from P. robusta in having more 
zooecial apertures per branch, and from P. acanthroporoides in 
having a greater number of acanthostyles. P. mirabilis has similar- 
sized apertures and acanthostyles to the Welsh material, but differs 
in having occasional basal diaphragms, which are absent in the 
Welsh specimens. 
Family PHYLLOPORINIDAE Ulrich, 1890 
Genus PHYLLOPORINA Foerste, 1887 
Phylloporina sp. Fig. 31 
MATERIAL. NHM PD 8384. 
