I.— INTRODUCTION. 
Two species of R 'aly sites are at present known from Australasian Silurian 
rocks and none from the Devonian. Ralysites australis is met with at 
Molong, N. S. Wales, and the other described, although at present unnamed 
species, comes from the Gordon River Limestone in Tasmania. Through the 
efforts of the Rev. J. M. Curran and Mr. C. A. Sussmilch on the one part, 
and Mr. C. Cullen, Collector to the Geological Survey of N. S. Wales, on the 
other part, a very fine series of specimens has been brought together from the 
Molong and Canobolas Districts. 
Many of these are of large size and very beautifully preserved, being 
weathered quite clear of matrix. They exhibit the essential anatomical 
characters quite as well in this condition as in sections prepared for the 
microscope ; upwards of one hundred specimens have in all been examined. 
The specific determination of these corals has been rendered most 
perplexing and difficult in consequence of the widely divergent views held by 
authors on the relative value of specific characters in Ralysites, and, in 
consequence, the chaotic state of the names applied to the various forms. 
Reference to old-world species is rendered still more difficult by the absence 
from descriptions, except on the part of a few writers, such as Fischer-Benzon, 
Nicholson, Lambe, &c., of all allusion to microscopic characters, other than 
in the most general terms. 
After working at the subject for some weeks, I felt that any hard-and- 
fast references to European or American species, in our present knowledge of 
these, would be so hopeless, that it became necessary to adopt some other 
method for the elucidation of the Australian corals. I accordingly 
endeavoured to arrange the latter, in the first instance in lots, simply on 
their macroscopic features, and, notwithstanding the contrary opinion held 
in other parts of the world of the difficulty in so separating species of 
Ralysites, I succeeded in grouping the specimens beyond my anticipations. 
That is to say, the external characters of our corals are sufficiently well 
marked to render possible the separation of a large parcel into groups of 
specimens possessing certain features in common that were afterwards 
found to exhibit similar microscopic details, which appeared to me to he of 
specific value. 
A. 
