284 Annals of the South African Museum. 



twos sporadically among the normal zooecia, but in places form 

 groups of many individuals to the exclusion of the normal zooecia. 

 There are two or three varieties of closed zooecia, but one variety 

 passes to another through intermediate forms. The commonest 

 resemble normal zooecia with a dome-shaped cap generally per- 

 forated (figs. 10, 11). These may become very short and tumid, and 

 in this form often occur many together (fig. 11). Other closed 

 zooecia are very small, about half the diameter of the normal (fig 12). 

 In some of these small ones the dome-shaped covering is elongated, 

 so that the zooecium appears like a small normal individual with a 

 small aperture and a somewhat tapering snout (fig. 12). In another 

 form the calcareous covering is flat — flush with the rim (fig. 12). 

 And in one zooecium of specimen 6 the perforation in the centre 

 of the flat cap is surrounded by a tiny rim of its own, raising the 

 perforation above the general level of the cap (fig. 12). 



Specimen 6 exhibits tumid areas of the zoarium apparently made 

 up of several zooecia and containing two or more apertures. These 

 are probably gonocysts. In one case a similar structure is apparently 

 made of a single bloated zooecium with a single aperture. This, 

 if reproductive in function, is a gonoecium. 



The zooecia are immersed, though their outlines are clearly marked 

 by a crack or a dark line on the zoarium. Just below the aperture 

 they bend upwards at almost a right angle, so that the plane of the 

 aperture is parallel or nearly parallel to that of the zoarium. The 

 surfaces of the zooecia are pitted with fine punctures. 



It is after much hesitation that this species has been placed 

 among the Eleidae, rather than in the genus Diastopora among the 

 Diastoporidae. The Eleidae ■■'- are characterised by the presence of 

 avicularia ; of closed zooecia ; of a non-terminal aperture ; of an 

 aperture not circular ; and of tubular zooecia. The last-named 

 character divides them from the Cheilostomes ; the first-named from 

 the Cyclostomes. But many Eleidge have no avicularia ; and as far 

 as Cretaceous forms are concerned no Diastopora has been described 

 with closed zooecia. A recent British species, Diastopora Sarniensis, 

 Norman, has been figured by Hincks f with some zooecia closed by 

 a flat cap perforated by a tubular pore very like that described in 

 specimen 6. And another generally-distributed recent British species, 

 Diastopora obelia (Johnston), figured by Hincks on the same plate, 

 has smaller zooecia, or "tul)ules," scattered among the normal. 



* See Gregory, Brit. Mus. Cat. Cret. Bry., 1899, pp. 287-290. 

 t British Marine Polyzoa (1880), pi. 66, fig. 8, p. 463. 



