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On some Peculiarities in the Structure of Stigm ari a . By Dr. Hooker, 

 F.R.S., &c, Botanist to the Geological Survey of the United 

 Kingdom. 



Much as has been said and written upon the structure and appear- 

 ance of Stigmaria, and long as this genus has been recognized as the 

 prominent feature in all discussions regarding the origin of coal, there 

 are still some very important points in its history which have hitherto 

 escaped observation. Of these, the most remarkable is the nature of 

 the surface previous to compression, and of the bases and attachment of 

 the rootlets. 



The surface of the Stigmaria has hitherto been supposed to be nearly 

 even and uniform, interrupted only by shallow scars, variously described 

 as circular by some, oblong by others, and lanceolate by still a third class 

 of observers, according to the state of the specimens they have ex- 

 amined. The depth of these scars seldom exceeds T Vth to ith of an 

 inch, in which respect the appearance of the surface of this fossil is so 

 constantly the same, that no geologist has at first sight recognized the 

 specimens figured at Plate 1, as belonging even to the genus Stigmaria. 



The above-mentioned two specimens are fragments of plants which 

 have evidently been preserved under little or no compression : tbe per- 

 fectly circular outline and uniform depth and figure of the cavities, 

 together with the cylindrical form of the organ they contain, all attest 

 this positively ; whilst the depression of the surface between these cavi- 

 ties, and the wrinkled substance, seem to indicate that a slight collapse 

 of the tissues composing the plant has taken place. 



After having convinced myself that the specimens of Lepidodendron, 

 figured at Plate 8, fig. 12, and that the portion of bark enclosed in the 

 fossil,* Plate 10, fig. 7, and indicated by the daggers, were the only 

 specimens that had come under my observation displaying any approach 

 to the original and unmutilated state of that genus, I was more than 

 ever assured of the extreme laxity of the tissues of the coal-plants, and 

 persuaded in my own mind that the ordinary run of specimens of all were 

 calculated to lead to erroneous views of their original appearance. Being 

 thus prepared to find familiar forms under a new aspect, I was not a 

 little gratified, when inspecting the cabinet of Miss Jukes, of Birming- 

 ham, to recognize the specimen of Stigmaria jicoides, figured at Plate 

 1, fig. 3, and which was obligingly lent for the use of the Survey. On 

 my return to town I found that a similar, but more perfect and much 



* See Memoirs of Geolog. Survey, in Essay on Lepidostrobus. 



