No. 4.] DAWSON — EOZOON CANADENSE. 231 



3, I took occasion to mention certain errors of Prof. Moebius, 

 due to his limited information on the subject of which he treats. 

 He admits two of these, which were particularly pointed out, but 

 taunts me with not producing others. This, however, would not 

 have been difficult had I been disposed to enter in detail into a 

 task so ungracious. Another example may be taken from his 

 plate XXXV, in which he represents together, and obviously for 

 comparison, portions of the pores or tubuli of the modern Poly- 

 trema, and an imperfect fragment of the proper wall of Eozoon. 

 and this more especially, as appears in the text, to show the 

 comparative fineness of the latter. But the specimen of Eozoon 

 is magnified only 75 diameters, while that of PoJytrema is mag- 

 nified 200 diameters, or in the proportion of 5625 to 40,000. 

 Again he has affirmed and repeats in his reply that the casts 

 of the canal systems of Eozoon do not present cylindrical forms 

 but are ^'■flat and irre^uZa?* branched stalk-like bodies." If they 

 appeared so to him, he must have possessed most exceptional 

 specimens. Some canals, especially the larger, no doubt have 

 flattened forms, particularly at their points of bifurcation ; but 

 this is comparatively rare, more especially in the vastly nu- 

 merous minute canals which are more frequently filled with dolo- 

 mite than with serpentine, I have indeed been able to detect 

 only a few out of very numerous specimens in which the majority 

 of the casts of canals are not approximately round in cross sec- 

 tion, even in the case of the larger canals. It is a question also 

 if some flattening may not be due to pressure ; and there are flat 

 stolon-like tubes which can scarcely be called canals.^ 



It occurs to me here to remark that Moebius seems to have 

 overlooked the extremely fine canals injected with Dolomite that 

 fill the upper and thinner calcite walls of the better preserved 

 specimens, and which in the thinner walls are nearly as fine as 

 the tubuli of the proper wall, into which in many cases they 

 almost insensibly pass where these last are themselves filled with 

 dolomite. Possibly these structures have not been present in 

 his specimens, or may have been destroyed or rendered invisible 

 by his methods of preparation, and if so this would account for 



* The forms of the canals are perhaps best seen in decalcified 

 specimens ; but Mr. Weston, who has done so much toward this in- 

 vestigation, has managed to cut slices so accurately at right angles 

 to the general course of groups of canals, as to show their round cross 

 sections with great distinctness. 



