Dr. G. J. Hinde—A New Ordovician Sponge. 57 
to be unfossilliferous, proved to be of considerable importance in 
showing the character of these organisms which flourished at this 
early epoch, and though the condition of the specimens was far 
from perfect, Sir J. W. Dawson was enabled from the materials 
obtained to describe eleven new species, which were placed in 
the genera Protospongia, Cyathospongia, Acanthodictya, Hyalostelia, 
Lasiothrix, and Halichondrites (Trans. Royal Soc. Canada, vol. vii. 
section iv. 1889, pp. 31-55, pl. i1.). With the exception of the 
species referred to the three last-named genera, of which the 
relationships are at present doubtful, these sponges belong to the 
group of Lyssakine Hexactinellids, of which the earliest traces are 
found in the Cambrian strata of this country and elsewhere. 
Since 1888, Sir J. W. Dawson has improved the opportunity afforded 
by passing the summer vacation in Little Métis in energetically work- 
ing at fresh excavations in the beach and cliff sections at that place, 
with the result of obtaining many fresh specimens, which confirm 
the characters of the forms already described. This last summer 
his search was further rewarded by finding a specimen of a new and 
very distinct form, which he has done me the honour to entrust to 
-me for description. As is the case with all the other sponges 
preserved in these black shales, this specimen is now in a flattened 
or compressed condition on the surface of the rock, and has the 
general appearance of a piece of coarse open network. Unfortunately 
the entire specimen could not be secured, and the portion on the slab, 
shown in the accompanying photograph, which has been reduced to 
about 3 the diameter of the original, probably represents less than 
one-half of the whole form. The original siliceous structure of the 
skeleton has now been replaced by pyrites, so that the form and 
dimensions of the spicules are but imperfectly shown. The same 
mineral change has affected all the other sponges in these beds, and, 
in fact, it is of very general occurrence wherever siliceous sponges 
are embedded in similar black carbonaceous shales. The specimen 
evidently belongs to a new genus, which is proposed below. 
PaLmOsaccvs,’ gen. nov. 
Cylindrical or sack-like sponges, with thin walls of rhombic 
meshes. The strands of the mesh-work consist of fascicles of slender 
rods, cruciform, and, perhaps, five-rayed spicules; the interspaces 
are either open or covered with a thin layer of irregularly disposed 
rods and cruciform spicules. No anchoring spicules have been found 
in immediate connection with the sponge, but there are in the same 
beds elongated anchoring spicules with ornamented spiral ridges 
which may perhaps belong to it. 
From Oyathophycus, Walcott (= Cyathospongia, Dawson, non Hall), 
which appears to be nearest allied, this genus is distinguished by 
_ the rhombic character and large size of the mesh-work; the generally 
* 
aa 
. 
similar structure both of the longitudinal and transverse strands of 
the mesh, and the greater development of rod-like spicules. The 
1 Tadatos, ancient; ocaxkos, coarse cloth, sack, strainer. 
