254 RECORDS OF THE AUSTRALIAN MUSEUM. 



Ohs. — A remarkable species, of a type simulating, on a cursory 

 examination, the growth of a compound astrfeiform coral, in 

 consequence of the frequent lateral union of the corallites. When 

 in this condition the latter assume, more or less, a polygonal out- 

 line, and such clusters are often of considerable extent. In 

 defining the genus Rominger'- says : — " The stems [corallites] are 

 rarely in intimate contact so as to form astrseiform masses," and 

 from its exceptional nature this species is peculiar. The inter- 

 spaces between these clusters are occupied by ordinary free and 

 generally smaller corallites, cylindrical in form. 



The weathered appearance of this coral is one that at once 

 attracts attention, as the tabulate areas stand well above the 

 general surface, simulating thick columellas, and around them 

 are seen the flat septal areas, the weathering out of the inter- 

 septal loculi reducing the septa to a ring of strong radii. One 

 specimen, however, exhibits the actual terminal surface of the 

 corallum, and whilst the flat septal area is still maintained, the 

 calices present a rather deep and pit-like appearance. Whenever 

 the corallites assume the composite condition, the lateral union 

 of the walls is generally, although not always, complete, for at 

 times a dividing line of matrix, more or less continuous, is visible 

 in places. 



The corallites may be described in general terms as short, the 

 corallum attaining its height by repeated parietal gemmation, 

 from a parent centre. The corallum is, therefore, at first formed 

 by a series of radiating corallites, which assume gradually a 

 vertical line of growth as the colony approaches maturity. Masses 

 at least six inches in height are thus formed, the largest corallite 

 yet measured having a diameter of nine millimetres. 



The proper walls and other tissues are represented in sections 

 by dark lines, backed by a lining of lighter secondary deposit, the 

 wall in each corallite being formed by the confluent peripheral or 

 proximal ends of the septa. 



Both transverse and longitudinal sections present some points 

 of great interest. In a transverse section one is struck with the 

 bi-structural nature of the endothecal tissue filling the interseptal 

 loculi. In some instances the loculi are comparatively devoid of 

 tissue at their proximal or peripheral ends, but display several 

 cycles of transverse dissepiments at their inner or distal ends. 

 Or, these partitions may occur regularly throughout a series of 

 loculi, the ordinary dissepimental vesicles so formed being again 

 subdivided in an irregular manner by additional tissue producing 

 a supplementary vesicular tissue. The septa are all primary, and 

 present traces of a distinct lateral denticulation, reminding one 

 of the genus lieliophyllum. 



2 Rominger — Geol. Survey Michigan — Report Lower Peninsula, 1873-76, 

 iii., 2, 1876, p. 120. 



