HALYSITES IN NEW SOUTH WALES — ETHERIDGE. 79 
corals, still sufficient details can be made out to elucidate the 
finer characters of our Haly sites. 
The mineral condition is very remarkable. The corals are 
preserved in a dark blue limestone, the tissues where unaltered 
being composed of the usual dark grey or brown sclerenchyma, 
the general infilling of all the intertabular spaces or old visceral 
chambers, being crystalline or granular calcite, the former in 
places with cleavage. Every here and there, however, the walls 
of the corallites are converted into a radiating siliceous mineral, 
or blebs of the same look as if forced into the walls ; there is 
every reason to believe that the latter is chalcedony, in the form of 
Beekite rosettes, a by no means uncommon mineral in our Lower 
Pakeozoic Invertebrata. In some cases these blebs occupy spaces 
within the corallites, breaking up the uniformity of the tabulate 
structure in a very marked manner. 
Notwithstanding this excessive alteration the external walls 
are quite discernible, and here and there the continuous epitheca 
on both the free sides of the laminae is visible also. As described* 
by Nicholson, the epitheca does not take any part in the “ form- 
ation of the partition which actually divides any tube from its 
neighbour on either side/' but the partitions are formed solely by 
the coalescent walls of the two contiguous corallites.” Further- 
more, the corallites are of two orders, as in the well known 
Haly sites catenulatus , Linn., thus at once distinguishing it from 
H. escharoides , Lamk. The larger, or normal corallites are oval, 
from three-quarters to one mm. in longest diameter, and the latter 
in the direction of the chain. In a macroscopic examination these 
may be at once distinguished by an outward bulging of the 
epithecated walls. The smaller corallites, or those of the second 
order, are ranged alternately with the larger, and are either round 
or quadrate, and each is enclosed by a thick wall of its own, 
distinct from the common or enclosing wall of the laminae. The 
position of these “interstitial tubes,” as they are termed by 
Nicholson, is equally discernible externally by a biconcavity of 
the wall opposite to each secondary corallite. The angles of 
junction of any two laminin that assist in forming a reticulation, 
or fenestrule, are always occupied by an interstitial corallite, which, 
in well weathered specimens, is visible with an ordinary pocket 
lens. Septa are absolutely wanting. 
The two sets of corallites become even more apparent in a 
vertical section. The normal tubes are closely tabulate, the 
tabula; horizontal, very regular, and equidistant, five in the space 
of one mm., enclosing between them more or less transversely 
elongated or quadrangular intertabular spaces. The interstitial 
tubes, on the other hand, are very narrow and pipe-like, sparsely 
* Nicholson — Tab. Corals Pal. Period, 1879. p. 227. 
