704 
DR W. T. GORDON ON CAMBRIAN ORGANIC REMAINS 
As in most of the other forms recorded, the interior of the cup becomes filled 
in towards the base by secondary structures. In the present instance this growth 
consists of irregular oblique tabulae from which offsets pass in all directions. The 
resulting tissue is very spongy and completely fills the base of the cup. In PI. V, 
fig. 53, the tissue is very evident. In PI. V, fig. 58, it is again seen, though it does 
not form such a marked feature. In both these examples the fixing lamellae are 
very distinct. 
The perfectly longitudinal section of PI. V, fig. 59, presents several interesting 
features. The fixing lamellae are not well preserved at the base, though they are 
indicated, and become more obvious at a higher level (Z). The tabulae are quite 
irregular in distribution, and the central tissue is obviously developed from the inner 
ends of the tabulae. The irregular offshoots from these tabular prolongations produce 
the coralloidal structure which is so marked in this figure. 
This new species may be defined as follows : — 
Cup small, vase-shaped. Fixed by lamellae which wrap round the base and 
spread out over the substratum. Porous structure of outer and inner walls similar 
(equivallum type) ; pores 4-6 per mm. Septa regular, perforate (5 pores per mm.) ; 
tabulae irregular, a mesh work rather than a porous platform ; mesh 8 or 9 per mm. 
Base of cup filled by coralloidal growth, the result of proliferations from the tabulae 
into the central space. 
Summary. 
The organic remains represented in two small pieces of limestone dredged 
from a depth of 1775 fathoms in lat. 62° 10 r S., long. 41° 20' W., are described. 
These consist of both plant and animal fragments and skeletons. The plants 
are calcareous algae and may be referred to the genus Epiphyton, Bornemann. 
The animal remains are spicules, probably from sponges, complete and frag- 
mentary cups of Archaeocyathinae, and sections of the carapace of trilobites. 
The sponge spicules may be referred to the groups Tetractinellida, Hexactinellida, 
and Heteractinellida. A peculiar forked type is also represented, but it is quite 
unlike the modern Lelapia in structure. 
The Archaeocyathinae belong to a number of different genera. Some of the 
species have been recorded from other parts of the world, but some are new forms. 
In certain of the known types, new structures have been recorded, and a more 
accurate specific description than was formerly given has thus been made possible. 
Taylor’s grouping of the family Archaeocyathidae has been revised and a new 
genus ( Thalamocyathus ) instituted. Thalamocyathus contains groups I to IV of 
Arcliaeocyathus as defined by that author. Thus in the Archaeocyathidae are 
included Arcliaeocyathus, Thalamocyathus, Etlimophyllum, Archaeofungia, and 
Pycnidocyathus. 
