92 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



considered, at the time, completely to corroborate the opinion 

 that they were distinct plants, but having recently examined 

 these specimens with more attention, and having had an oppor- 

 tunity to compare them with others, since discovered, I am 

 enabled, I believe, to point out that these curious columnar forms 

 are merely casts of the medullary cavities of stems or branches of 

 trees, similar to that at Darlaston, lately described ; for, upon one 

 of the fossils alluded to, the interior of which is composed of a 

 series of horizontal plates, we find that a part of the woody tissue 

 of the tree is still attached to the column, and another specimen 

 which shows, upon its exterior, traces of the characteristic rings, 

 exhibits also a considerable portion of adhering wood. But more 

 direct evidence is afforded by a branch, now converted into iron- 

 stone (see fig. a), down the centre of which a distinct arrangement of 

 similar plates may be observed, occasionally anastomosing or rather 

 merging one into the other, exactly as the external forms of 

 Sternbergias would lead us to expect ; and a smaller specimen from 

 another district (North Staffordshire) appears still more clearly to 

 show this connection. I may also mention that the pith of recent 

 wood (Juglandacece), on losing its moisture, has occasionally been 

 found to separate, after a manner somewhat similar (b). It is rare, 

 however, that specimens in the fossil state, retaining this structure, 

 have been met with, the plates having only been preserved when 

 mineral matter has atomically replaced the cellular tissue, the 

 plants having previously been in a dry or partially decayed state. 

 In general, the material has filtered into and filled up the inter- 

 stices, producing the usual cross-barred or ringed appearance of 

 these fossils. Sometimes, cylindrical casts may be found which 

 are marked externally by sharp, longitudinal, irregular strias, re- 

 presenting probably a portion of the medullary sheath. The 

 whole of the cellular tissue, in such cases, has previously been 

 carried away ; but a fine tree at Darlaston has afforded proof that 

 under peculiar circumstances the mineralizing process may com- 

 mence soon after the fall of the plant. Thus, in all probability, 

 the central column of that specimen will retain the cellular struc- 

 ture. In conclusion, I may allude to the isolated and peculiar 

 fragmentary state in which these cylindrical bodies occur. We 

 find no attached branches, no roots, no leaves or leaf-scars ; 

 indeed, there is a total want of every part of a vegetable, by which 

 these fossils might be identified as distinct plants : for the car- 

 bonaceous covering, now and then met with, and supposed to have 

 been the bark, being sometimes very irregular is most likely acci- 

 dental, or in some cases may arise from portions of attached wood 

 having become converted into coal. Should the discovery of 

 further specimens more completely prove these views respecting 

 Sternbergiae to be correct, we may perceive from their occurrence 

 in, I believe, all our coal fields, how frequently a small cylindrical 

 column alone remains when every other vestige of the magnificent 

 plant from which it originated has been lost. 



