682 
DR W. T. GORDON ON CAMBRIAN ORGANIC REMAINS 
measurement was possible ; where the skeletal structures were preserved in silica 
in a calcareous matrix (as in the South Australian types described by Taylor), the 
details were etched out by means of acid ; where the skeletons were enclosed in the 
matrix, thin sections or polished sections were employed. There is little doubt that 
the preparation of thin sections is the best means to elucidate the minute details, 
but there are difficulties, as pointed out by Hinde, # in obtaining a proper orientation 
of such sections. This is seen in a marked degree in Bornemann’s memoir, where 
many of the figures are from very oblique sections. 
In the present instance the material was very scanty, and to prevent waste small 
sections of individual specimens were prepared. With a certain amount of care in 
the orientation of these, it has been possible in most cases to show the following 
characters : — - 
(a) The nature of the fixation of the skeleton to the substratum. 
( b ) The appearance in cross-section at or near the top of the specimen. 
(c) The size and arrangement of the pores on the walls, septa, and tabulse. 
As mentioned above, the material was not abundant, and in some cases all these 
characters have not been observed. In certain genera emendations have been made 
on the descriptions of species already recorded, and a few new species have been 
added to the group. 
Before passing to a detailed description of the forms examined, it is necessary 
to devote a word or two to the material investigated and the locality from which it 
was obtained. All the specimens were enclosed in small pieces of a white limestone 
broken from a block which was dredged from a depth of 1775 fathoms in the Weddell 
Sea, in lat. 62° 10' S., long. 41° 20' W., Station 313 (text-fig. 2, X). When the fragments 
were glued together, prior to being cut into sections, they formed two pieces each under 
a pound in weight. Both must have belonged originally to the same mass, though 
it is doubtful if they represented the whole of the original block, since they did not fit 
exactly together. This is worthy of record, as erroneous statements have been made 
regarding the amount of material available.! The outer crust of the fragments 
showed considerable weathering effects, so that a layer of white powdery material 
fully one-eighth of an inch thick encrusted the whole external surface. 
The position in the north of the Weddell Sea from which the boulder was 
dredged cannot be considered as marking the position of any limestone band, 
for the block occurred among other debris evidently derived from a deposit of 
material dropped by melting icebergs. The ocean drift near the locality is to the 
north and east, so that the bed from which the material was originally torn must 
lie further into the Antarctic continent. (Other forms of Archseocyathinse have been 
recorded from the Beardmore Glacier moraines, and were probably carried from a 
* Hinde, G. J., Q.J.G.S. , vol. xlv, p. 133, footnote, 
f British Association Report : Meeting in Australia, 1914, p. 413. 
