374 J. W. Dawson on fossils from the Laurentian of Canada, 
and in certain parts of those beds, that well-characterized speci- 
mens can be found. I may also repeat here that in the original 
examination of Hozoon, in the spring of was furnished 
y Sir W. E. Logan with specimens of all these limestones, and 
also with serpentine-limestones of Silurian age, and that, while 
all possible care was taken to compare these with the specimens 
of Hozoon, it was not thought necessary to publish notices of 
the crystalline and concretionary forms observed, many of 
which were very curious and might afford materials for other 
papers of the nature of that criticised in the above remarks. 
organic structure, since no conceivable process of crystallization 
i na 
posed on exactly the same crystalline system with the calcite 
which includes it, the two substances being mineralogically 
pomowensons and only structurally distinguishable by the f 
fect of their junction-surfaces on the course of faint rays ° 
light transmitted through them.—w. B. ©.] 
: [nhs proveding in, r was drawn out in part by the observa 
tion of Messes. a ona Rowney on the Preation published 2 
the Quarterly Journal of the Geological Society, vol. xxii, pages 
185 to 217, and illustrated by two plates. The following 2° 
the Summary and Conclusion with which the paper of Messrs. 
King and Rowney closes—Eps.] ge 
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