LOWER CARBONIFEROUS BRYOZOA 
lexites paradoxus sp. nov. Figs 3a, 4-5, 8 
{OLOTYPE. BMNH PD9410; Upper part of the Glencar Lime- 
fone (Viséan, Asbian), Carrick Lough, County Fermanagh. 
ARATYPES. BMNH PD9411-9429; TCD.34012-34014, 34125, 
4127, 34164, 34167, 42593c, all from the same locality and 
/orizon as the holotype. TCD.42514-42515, Upper part of the Glen- 
Limestone (Viséan, Asbian), Sillees River, County Fermanagh. 
ERIVATION OF TRIVIAL NAME. This Hexites species has between 
e and eight rows of autozooecial apertures, unlike the type species 
thich has six, so therefore is a paradox. 
IAGNOSIS. Hexites with a delicate dendroid zoarium. Branches 
e straight to gently curved with a polygonal to sub-polygonal 
_foss-section. Lateral branches diverge nearly perpendicular to the 
ain stem and are infrequently developed. Autozooecia developed 
. five to eight longitudinal rows around the complete branch. The 
“verse surface is seen only as a very thin groove. Autozooecial 
ertures are small, oval to elliptical in shape. Apertural rows are 
vided by sharp distinct longitudinal ridges. Stylets developed on 
_ dges and occasionally between successive autozooecial apertures. 
JESCRIPTION. Colonies are small, delicate, and dendroid. Branches 
“fe straight and of constant diameter along their length. Branch 
fOss-sections are polygonal to rarely sub-polygonal. Lateral branches 
~a similar diameter diverge at unknown intervals perpendicular to 
ie main branch. There is a very slight increase in branch width at 
mifications. The largest fragment examined measured 9.8 mm in 
ngth. 
Autozooecia are developed in five to eight longitudinal rows 
ound most of the branch. In some specimens the reverse surface is 
ig. 3. Measurements taken on arthrostylid cryptostomes in this study. a, Hexies paradoxus sp. nov.; b, Nematopora hibernica Sp. NOV.; ¢, 
Pseudonematopora planatus sp. nov. BW = Branch diameter; AD1 = Autozooecia apertural diameter measured parallel to growth direction; AD2 = 
Autozooecia apertural diameter measured perpendicular to growth direction; AS1 = Autozooecia apertural spacing measured parallel to growth direction; 
AS2 = Autozooecia apertural spacing measured perpendicular to growth direction; AR = Number of longitudinal apertural rows around zoarium; Z2 = 
| Number of autozooecial apertures contained within a 2mm line measured parallel to growth direction. 
represented by a thin groove (Fig. 5). Autozooecia arise from a thin 
central axis and diverge from it a low angle. Chamber bases are 
slightly inflated. Chambers are sublinear in shape, 0.60 to 0.71 mm 
in length and at least ten times as long as wide. In cross-section they 
are triangular to polygonal in shape. The vestibule, which shallows 
distally, is orientated at an angle of between 45° and 60° to the 
zoarial surface. The distal wall is thin with slight thickening of the 
proximal frontal wall. Hemisepta and diaphragms are not present. 
Autozooecial apertures (0.28 x 0.14mm) occur in longitudinal 
rows that are separated by a sharp to rounded ridge 0.08 mm wide. 
They are oval to elliptical in shape, and occasionally narrow distally. 
They are regularly spaced one diameter apart within rows and one to 
two diameters apart between rows. Autozooecial aperture size is 
marginally greater and apertural spacing slightly less in those rows 
closest to the groove on the reverse of branches. 
One to two rows of small short acanthostyles 0.02mm wide occur 
on the crest of ridges. Interapertural areas may be smooth or be 
decorated with up to twelve acanthostyles in three rows. 
Table 1 Measurements of Hexites paradoxus (in mm). N=18. 
NM Xx Mn Mx CVw CVb 
BW 136 0.59 0.37 0.72 31,715) 8.43 
ADI 152 0.28 0.20 0.43 10.55 7.00 
AD2 tS7 0.14 0.08 0.22 10.88 6.64 
AS1 142 0.22 0.09 0.42 14.08 4.78 
AS2 158 0.26 0.13 0.40 14.81 7.31 
DISCUSSION. Hexites is easily recognised by the arrangement of 
autozooecia in well-developed longitudinal rows, with strong 
interapertural ridges. 
