. Bulletin of the British Museum (Natural History). 118 PITT AND TAYLOR. Figs 115-116 Heteropora keepingi Gregory, thin sections. Fig. 115, USNM 69872, syntype of Ceriopora dimorphocella Canu & Bassler, tangential section, x 74. Fig. 116, BM(NH) D55216, transverse section of exozone showing strongly moniliform zooecia, x 33. Description. Zoaria (Fig. 109) are dendroid with thick branches, 8-15 mm in diameter, which bifurcate at intervals. Distal branch growth tips are blunt and rounded. Maculae, marked by concentrations of kenozooecia (Fig. 114B), are spaced about 3-4 mm apart on
. Bulletin of the British Museum (Natural History). 118 PITT AND TAYLOR. Figs 115-116 Heteropora keepingi Gregory, thin sections. Fig. 115, USNM 69872, syntype of Ceriopora dimorphocella Canu & Bassler, tangential section, x 74. Fig. 116, BM(NH) D55216, transverse section of exozone showing strongly moniliform zooecia, x 33. Description. Zoaria (Fig. 109) are dendroid with thick branches, 8-15 mm in diameter, which bifurcate at intervals. Distal branch growth tips are blunt and rounded. Maculae, marked by concentrations of kenozooecia (Fig. 114B), are spaced about 3-4 mm apart on the zoarial surface. Zoarial bases are expanded but not extensive. Autozooecial apertures are subcircular to polygonal, small, and surrounded by smaller, more angular kenozooecial aper- tures (Fig. 114C). Mural spines may be visible within both autozooecial and kenozooecial apertures; they are densely concentrated, taper distally, have rounded ends and are up to about 0 01 mm long. Brood chambers (Fig. 114D) are visible as shallow depres- sions, approximately 2 mm in diameter, on the colony surface in the positions of maculae. Intact roofs have not been observed in hand specimens. Most of the autozooecia and kenozooecia below the chamber are occluded by a calcified layer forming the floor of the chamber. Thin sections show the coaxial endozone (5 mm in diameter in D55216) and exozone, with moderately thick zooecial walls in the endozone and thick, distinctly moniliform walls in the exozone (Fig. 116). Diaphragms are absent or rare, and have aborally convex diaphragms. Brood chambers have not been observed in section. Measurements. TAM, mean 0-10 mm; KAM, mean 0-04 mm. Remarks. Heteropora nummularia Canu & Bassler, 1926, described from Faringdon, is represented by a single, worn specimen (USNM 69853). This is a flat, discoidal colony sharing with H. keepingi a similar arrangement of auto- zooecial and kenozooecial apertures which are, however, generally smaller in H. nummul
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