](•> 



STIGMARIA FICOIDES. 



The rarity of small branching specimens, along with other facts, seems to 

 show that after the first two consecutive bifurcations occurred within a limited 

 distance from the central stem, no others took place in the true roots. The long, 

 had seen no examples of Stigmarian roots less than two inches in diameter. Like Mr. Steinbaur, 

 I am convinced that such examples of Stigmarian roots, terminating like thick cucumbers, were 

 abnormal, although my friend Sir William Dawson tells me that in Canada he has found ordinary 

 roots terminating in this obtuse form more frequently than we do in Great Britain. In all 

 probability some accidental cause had arrested the further longitudinal growth of such roots, 

 though they continued to swell transversely. Unquestionably the specimens described above, along 

 with others in my cabinet, demonstrate that these roots ultimately tapered away to extremely 

 small twigs. Proof of this was abundantly furnished by the trees in the Oldham Forest, already 

 referred to. It is possible that some of the obtuse specimens spoken of above are fragments of 

 examples like one described and figured by Mr. Richard Brown, of which figure the accompanying 

 Xylograph 6 is a copy. This memoir is entitled " Description of Erect Sigillarise with Conical 



Xtlogbaph 6. 



k 



Tap-roots, found in the Boof of the Sydney Main Coal in the Island of Cape Breton " (' Quarterly 

 Journal of the Geol. Soc. of London,' vol. v, p. 354). The specimen figured is the under surface of the 

 base of a stem, in which the four primary roots divided and subdivided so rapidly that thirty-two 

 roots were seen within a circle of eighteen inches in diameter. " Besides this," the author says, 

 " there are four large tap-roots in each quarter of the stump, as shown in fig. 7, and about five inches 

 beyond these a set of smaller tap-roots, striking perpendicularly downwards from the horizontal 

 roots, making forty-eight in all, viz. sixteen in the inner and thirty-two in the outer set." 

 Page 358, " The inner set of tap-roots vary from two to two and half inches in length, the diameter 

 at their junction with the base of the trunk being about two inches." " The outer set are much 

 smaller, being about one inch in diameter at their junction with the horizontal roots, and from one to 

 one and a half in length. A thick tuft of broad, flattened rootlets radiates from the terminations of 

 the tap-roots and a few indistinct areolae are visible on their sides." 



Bemembering that in many recent Lycopods the roots branch alternately in vertical and horizontal 

 planes, the above description suggests that some Stigmarian roots have attempted to do the same 

 thing, though more or less abortively, owing possibly to unfavorable conditions preventing them from 

 penetrating the soil. At any rate, we learn from Mr. Brown's description that such undeveloped roots 

 were capable of being produced exceptionally, which fact renders probable my explanation of the obtuse 

 forms to which this note refers. It is possible, however, that the above plant may have been a form 

 distinct from our common type. If the letters i, k, I, and tn, represent the subdivisions between the 



