1864.] CARPENTER SXRXJCTUEE OP EOZOON, 59 



pearances I regard as due to the mode of preservation rather than to 

 any original differences, certain portions less altered than the others 

 presenting the ordinary typical characters. 



Two slices of limestone from the British Islands, and supposed to be 

 Laurentian, have been compared with the Canadian limestones above 

 noticed. One is a serpentine marble from Tyree. It appears to be 

 fragmental, hke some of the Laurentian limestones of Canada, and 

 may contain fragments of Eozoon. The other is from lona (?). It 

 presents what I regard as traces of organic structure, but not, in so 

 far as can be made out, of the character of Eozoon. Both of these 

 limestones deserve careful microscopic examination. 



EXPLANATION OF PLATES VI. & VII. 



Illustrating the Structure of Eozoon. 



Plate VI. 



Specimen from Grand Calumet. Natural size. The white layers are carbonate 

 of lime ; the dark layers are wliitish pyroxene. 



Plate VII. 



Fig. 1 . Specimen from Bm-gess. Natural size. The wliite layers are dolomite ; 

 the black layers are dark-green loganite. 



2. Transverse section of Eozoon from Grenville, magnified 25 diameters : 



{a) tubuli ; (6) septal orifices, &c. ; (c) large chambers. 



3. Horizontal section of Eozoon from Grenville, magnified 25 diameters : 



(a) systems of tubuli ; (6) secondary chamber. 



4. One of the systems of tubuli cut transversely, magnified 100 diameters. 



5. Part of a system of tubuli cut transversely, magnified 200 diameters. 



3. Additional jS'ote on the Structure mid Aeeinities of Eozoon 

 Canadense. By W. B. Carpenter, M.D., F.E.S., F.G.S. 



[In a Letter to Sir WUliam E. Logan, LL.D., F.E.S., F.G.S.] 

 [Plates VIII. & IX.] 



The careful examination which I have made — in accordance with 

 the request you were good enough to convey to me from Dr. Daw- 

 son, and to second on your own part — into the structure of the very 

 extraordinary fossil which you have brought from the Laurentian rocks 

 of Canada*, enables me most unhesitatingly to confii'm the saga- 

 cious determination of Dr. Dawson as to its Rhizopod characters and 

 Foraminiferal affinities, and at the same time furnishes new evi- 

 dence of no small value in support of that determination. In this 

 examination I have had the advantage of a series of sections of the 

 fossil much superior to those submitted to Dr, Dawson ; and also of 

 a large series of decalcified specimens, of which Dr. Dawson had only 

 the opportunity of seeing a few examples after his memoir had been 

 written. These last are peculiarly instructive; since, in consc- 



* The specimens submitted to Dr. Carpenter were taken from a block of 

 Eozoon rock, obtained in the Petite Nation Seigniory, too late to afford Dr. 

 Dawson an opportunity of examination. They are from the same horizon as 

 the Grenville specimens. — W. E. L. 



