. Bulletin of the British Museum (Natural History), Geology. 160 C. J. BUTTLER. Fig. 8 Longitudinal sketches of the new species described from the Llanbedrog Mudstones. a, Stigmatella oakleyi. b, Pedrogopora taylori. c, Diplotrypa nontabulata. often constricting chamber width, producing beaded appearance. Description. Zoaria massive and hemispherical, on average 9-5 mm in diameter. All specimens are fragmentary and no bases are preserved. Autozooecia bud from the basal lamina and curve upwards to the zoarial surface. Autozooecial walls are straight throughout the zoaria, and no differentiation
. Bulletin of the British Museum (Natural History), Geology. 160 C. J. BUTTLER. Fig. 8 Longitudinal sketches of the new species described from the Llanbedrog Mudstones. a, Stigmatella oakleyi. b, Pedrogopora taylori. c, Diplotrypa nontabulata. often constricting chamber width, producing beaded appearance. Description. Zoaria massive and hemispherical, on average 9-5 mm in diameter. All specimens are fragmentary and no bases are preserved. Autozooecia bud from the basal lamina and curve upwards to the zoarial surface. Autozooecial walls are straight throughout the zoaria, and no differentiation between exozone and endozone can be distinguished. Auto- zooecia are large with an average diameter of 0-38 mm x 0-44 mm, and are polygonal-circular in transverse section through- out the colony. Diaphragms are absent or very rare in autozooecia; if present they occur in the outermost parts of the autozooecia. Mesozooecia present, often in abundance, in all zoaria and originate throughout the colony. Maximum diameter averages 0-23 mm; however, there is a large range (0-08-0-44 mm). Mesozooecia are polygonal, often triangular or rectangular, frequently positioned at the autozooecial corners. Meso- zooecia contain abundant diaphragms along their entire length. These are basal diaphragms deflected orally at their junctions with the zooecial walls, and spaced on average 0-16 mm apart in the endozone and 015 mm in the exozone. Mesozooecia are often constricted at the position of the diaphragms, producing a beaded appearance in longitudinal section. Autozooecial walls are thin which, combined with poor preservation, results in difficulties in distinguishing wall microstructure. In one specimen (PD 8174) the walls thicken very slightly close to the zoarial surface, reaching a thickness of 0-032 mm. There is an indistinct dark band at the centre of the wall, bordered by lighter bands on either side which have a vague laminar appearance. Within the main body of the zoarium the walls ar
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