692 
DR W. T. GORDON ON CAMBRIAN ORGANIC REMAINS 
wall lias 6 rows of pores per interseptum, which is '5 mm. wide.* Thus there are 
10-12 pores per mm. on the outer wall. The septa also are porous. 
The Antarctic specimen has 7 pores per mm. on the inner, and 10 pores per 
mm. on the outer wall ; the septa are porous, and the general shape seems to 
conform to that of the Sardinian species. All these characters confirm the reference 
of the type to T. ichnusse. Since both T. infundibulum and T. ichnusae are re- 
presented by single specimens, and by single sections of these examples in each 
case, the specific features have been a matter of deduction rather than observation. 
The clearest evidence is the size of pore, and unfortunately Bornemann laid little 
stress on this point. Yet it is probably much more constant and important than 
the external shape, a character often rendered useless by distortion. Indeed, some 
re-examination of the Sardinian types is urgently required. 
Thalamocyathus flexuosus, sp. nov. 
Under the specific name of sinuosus, Bornemann! has described a Thalamo- 
cyathus type with narrow intervallum and characteristic plicated outline in trans- 
verse section. A well-marked feature in addition to the habit is the presence of 
large pores on the inner wall and small ones on the outer, there being 3 per mm. 
and 10 per mm. respectively 4 The great difference in size is also seen in other 
figures illustrating the work. 
A rather similar form occurs in the Weddell Sea material, as a number of small 
fragments but no complete cup has been obtained. As a result of the flexuous outline 
(PI. Ill, fig 27, a), it has been a matter of some difficulty to determine which is the 
outer and which the inner wall. The intervallum is narrow — about '5 mm. — and as 
the septa are also closely set the interseptal loculi are nearly square in transverse 
section (PI. Ill, fig. 27). On account of the exceedingly narrow intervallum no 
very good longitudinal sections of the wall could be made in series, but the two 
figured (PI. Ill, figs. 28 and 29) are from successive sections, and illustrate in some 
way the porous character of the walls. The first point to be noted is that the pores 
are almost equal on each wall, a feature only recorded so far from specimens of 
Australian origin — the “ equivallum ” type of Taylor. By measurement, however, 
it is found that on one wall the pores number 6 per mm., and on the other 8 per mm., 
so that a slight difference does occur. Another point of difference lies in the fashion 
in which the septa meet the two walls. In one case — That with the smaller pores — 
the septa meet the wall between rows of pores (PI. Ill, fig. 29, s ), but they meet the 
other wall along a pore-row, i.e. there are “ stirrup ’’-pores, the one perforation 
allowing communication from the exterior to two adjacent loculi (PI. Ill, fig. 28, b). 
The septa appear to be imperforate apart from the stirrup-pores at their ends. Since 
* Bornemann, loc. cit., p. 55. 
t Bornemann, loc. cit., p. 57 ; and Geol. Zeitschr., 1854, p. 704. 
X Calculated by measurement from Bornemann, loc. cit., Taf. xii, figs. 6a, 66. 
