J. W. Dawson on fossils from the Laurentian of Canada. 367 
difficulties hitherto experienced in reconciling the results of 
analyses, particularly of silicates. On this point M. Lechartier 
of Paris has recently published some interesting facts, relating 
especially to the impurities detected in staurotide.* 
New Haven, Oct. 10th, 1867. 
Art, XXXIX.— Notes on Fossils recently obtained from the Lauren- 
tian Rocks of Canada, and on objections to the organie nature of 
Eozwon; by J. W. Dawson, LL.D., F.R.S., F.G.S., with Notes 
by W. B. Carpenter, M.D., F.RB.S. 
a. General Appearance.—The fossil is of a clavate form, six 
contrast to the dark stone filling the chambers. The specimen 
lies flat in the plane of stratification, and has probably suffered 
Some compression. Its septa are convex toward the broad end, 
right angles to the septa, and 
filled with carbonate of lime, similar in general appearance to 
* Bulletin de la Soc. Chimique, May, 1865, p. 375. 
