1915] PALAEOZOIC FOssILS FROM HupDsON Bay. 13 
A transverse section (Pl. V, Fig. 5) at about the middle of the 
specimen, where the diameter is 31 mm., shows 50 long primary septa 
which extend inwards for a length of 11 mm.: towards the centre they 
coalesce and lose their identity in a mass of reticulated tissue. Secon- 
dary septa appear between the primaries and extend inwards for 6 mm. 
This outer zone is thickened by deposits of calcareous matter and 
shows no structures besides the septa. Between the inner ends of the 
secondaries and the central area of reticulated tissue, inwardly curved 
dissepiments appear in the interseptal loculi. The transverse section, 
therefore, presents three well defined zones—an outer ring with primaries 
and secondaries, a middle zone with primaries and dissepiments and an 
inner reticulated area. 
A longitudinal section (Pl. V, Fig. 4) shows no further structures 
in the outer zone. The intermediate area, as the section is not exactly 
median, shows the severed edges of some primary septa and upwardly 
directed dissepiments. On entering the central area the dissepiments 
assume a more horizontal direction and present, to some extent, the 
characteristics of tabula. This central area shows a rather indistinct 
arrangement of dissepiments and septa, and, on the whole, suggests a 
transition between the structure typical of Strepielasma and that which 
characterizes Zaphrentis. There is more evidence of irregularity in 
the vertical than in the horizontal elements of the reticulation. 
In the preliminary report this specimen, together with others from 
the same locality, was referred to S. corniculum, Hall. The straight 
form of the corallum, its greater size, its smooth exterior, and the rela- 
tively long secondary septa, seem to bring the form closer to S. rusticum, 
Billings, as redefined by Lambe. The internal structure is very like 
that figured by Lambe, but the secondary septa are relatively longer 
and the internal structures of a coarser type in our specimen; never- 
theless, in the absence of better material, the form may reasonably be 
ascribed to Billings’ species. 
Locality—Lower rapids, Shamattawa river, Manitoba. 
Horizon—Ordovician. 
No. 285 S. Royal Ontario Museum of Palaeontology. 
STREPTELASMA INTEGRISEPTATUM, Sp. 10. 
Plate V, Figures 1, 2 and 3. 
This species is described from two very imperfect specimens which 
nevertheless present definite features not seen in species hitherto des- 
cribed. 
