Canada 
Geological Survey 
Victoria Memorial Museum 
BULLETIN No. 1 
VII . — Two New Species of Tetradium . 
By Percy E. Raymond. 
The following species of Tetradium seem to be distinguished 
from all described species by their habit of growth. Subdi- 
visions based upon nice distinctions in the characters of the cells 
cannot be attempted until the whole genus is thoroughly re- 
studied. 
Tetradium halysitoides, sp. nov. 
Plate VI, fig. 3; Plate VII, fig. 1. 
Corallum roughly hemispheric, composed of square corallites, 
which are joined into intersecting and anastomosing laminae of 
single (sometimes double) layers of tubes united along the whole 
of their adjoining sides, as in Holy sites. The tubes are nearly 
square in section, and show four primary septa, which extend 
over halfway to the centre. The laeunse between the rows of 
tubes are rather large, and laminae are usually made up of single 
rows of cells, although in some cases they are in double rows, as 
is shown in the upper part of the photograph. The weathered 
natural vertical section shown in the figure, shows rod-like 
supports extending across the lacunae from one lamina to another. 
The best corallum collected is 70 mm. in diameter, but larger 
specimens were seen in place.. The corallites average about 1 
mm. in diameter. 
Locality.— The species seems to be fairly common in the lower 
part of the Lowville, near lot 25, con. VI, of Carden, Ontario, 
