r 



18 



CANADIAN FOSSILS. 



In other cases a concretionary action has been established, Tvhereby 

 circular radiating spots liaTO been produced, interfering with the struc- 

 ture ; and in some instances this goes so -far as to give the whole mass a 

 sort of oolitic appearance. (Fig. 23.) 



By preparing and comparing with each other a large number of slices, 

 I have been able to recognize, under all these different states of preserva- 

 tion, the same structures originally described by me in the paper above 

 cited. All present cylindrical woody fibres, marked with irregular spiral 

 lines, and indications, perhaps illusory, of small round pores placed at 

 unequal intervals. The woody fibres are of groat length, but not closely 

 in contact with each other, giving to the wood a lax appearance, like that 

 in very young Coniferous stems. The fibres are not placed in regular 

 radiating series, but are divided into wedges by radiating bands repre- 

 senting the medullary rays, and there are distinct lines of growth in which 

 the fibres are of smaller diameter than elsewhere. I figure some of these 

 appearances as presented in the specimens more recently obtained.* 



With the exception of the lines of growth, I have failed to observe any 

 change of structure in passing from the circumference to the centre. No 

 pith has been observed, and the bark, when present, is thin and coaly. 

 The roots have precisely the same structure with the stems, except that the 

 fibres appear to be a little larger, and with the walls less thickened. (Fig. 

 27). 



In all the specimens there are evident indications of medullary rays, 

 in radiating bands and lenticular spaces traversing the wood ; but the 

 structure of the rays has perished, as one frequently observes in old and 

 •weathered trunks of modern trees. This would either indicate that the 

 medullary rays were lax and perishable, or that all the specimens have 

 been much lecayed before fossilization. (Figs. 20, 21, 22, 25). 



In one inut .^nce a large branch was observed to be given off', and on 

 other trunks knots representing the attachment of small lateral branches, 

 like those of ordinary pines, were found. The most remarkable external 

 marking consists in certain transverse swellings which give to the trunk 

 an irregularly articulated appearance (Fig. 19). These swellings are 

 connected with a gnarled appearance of the external layers of the wood, but 

 the internal layers appear smooth, as if the structure supervened in an 

 aged condition of the trunk. Two explanations of it occur to me : — 

 (1.) The swellings may mark Unes from which whorls of small branches 



• In some of the more perfect specimens the fibres appear as if connected with each other 

 bj fine reticulations or by the dark bars of the thickened wails passing from one to another. 

 This curious appearance it is difficult to explain. It may either depend on the state of pre- 

 •ervation of the specimens or on some peculiarity of structure at present unknown 

 to me. 



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