118 
Proceedings of the Royal Irkh Academy. 
occurrence in Laurentian rocks of definite forms resembling the Silu- 
rian Stromatopora, and dissimilar from any concretions or crystalline 
structures found in these rocks. With his usual sagacity, Sir William 
added to these facts the consideration that the mineral substances oc- 
curring in these forms were so dissimilar as to suggest that the forms 
themselves must be due to some extraneous cause rather than to any 
crystalline or segregative tendency of their constituent minerals. These 
specimens, which were exhibited by Sir William, as probably fossils, 
at the meeting of the American Association in 1859, and noticed with 
figures in the E-eport of the Canadian Survey for 1863, showed under 
the microscope no minute structures. The writer, who had at the 
time an opportunity of examining them, stated his belief that if fossils, 
they would prove to be not Corals but Protozoa. 
In 1864, additional specimens having been obtained by the Survey, 
slices were submitted to the writer, in which he at once detected a 
well-marked canal-system, and stated, decidedly, his belief that the 
forms were organic and foraminiferal. The announcement of this 
discovery was first made by Sir W. E, Logan, in Silliman's Journal 
for 1864. So far, the facts obtained and stated related to definite 
forms mineralized by loganite, serpentine, pyroxene, dolomite, and 
calcite. But before publishing these facts in detail, extensive series 
of sections of all the Laurentian limestones, and of those of the altered 
Quebec group of the Green Mountain range, were made, under the 
direction of Sir W. E. Logan and Dr. Hunt, and examined microsco- 
pically. Specimens were also decalcified by acids, and subjected to 
chemical examination by Dr. Sterry Hunt. The result was the 
conviction that the definite laminated forms must be organic, and 
farther, that there exist in the Laurentian limestones fragments of such 
forms retaining their structure, and also other fragments, probably 
organic, but distinct irom Eozoon. These conclusions were submitted 
to the Geological Society of London, in 1864, after the specimens on 
which they were based had been shown to Dr. Carpenter and Professor 
T. R. Jones, the former of whom detected in some of the specimens an 
additional foraminiferal structure — that of the tubulation of the proper 
wall, which I had not been able to make out. Subsequently, in rocks 
at Tudor, of somewhat later age than those of the Lower Laurentian 
at Grenville, similar structures were found in limestones not more 
metamorphic than many of those which retain fossils in the Silurian 
system. I make this historical statement in order to place the question 
in its true light, and to show that it relates to the organic origin of 
certain definite mineral masses, exhibiting not only the external forms 
of fossils, but also, their internal structure. 
In opposition to these facts, and to the careful deductions drawn 
from them, the authors of the Paper under consideration maintain 
that the structures are mineral and crystalline. I believe that in the 
present state of science such an attempt to return to the doctrine of 
'^plastic-force" as a mode of accounting for fossils would not be 
tolerated for a moment, were it not for the great antiquity and highly 
crystalline condition of the rocks in which the structures are found, 
