360 [Feb. 21, 



Stembergi^ would lead us to expect ; and a smaller specfmen 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 (^>). 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 stri^, 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 bai-k, 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 

 Sternbergige 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. 



4. On the Thalassina Emeeh, a fossil Crustacean, forwarded hy 

 Mr. W. S. Macleay, from New Holland. By T. Bell, F.R.S., 

 Professor of Zoology in King's College, London. 



This fossil, forwarded from Mr. Macleay and brought by Lieu- 

 tenant Emery from Australia, belongs to the typical genus of a 

 very remarkable family of decapod Crustacea, the Thalassinidce 

 ( Thalassiniens of Milne Edwards), as Mr. W. S. Macleay has sur- 

 mised. Of the genus in question, Thalassina, but a single recent 

 species is known, and little has been ascertained respecting its 

 habits. There is, however, reason to believe, that in this respect 

 it agrees with the species most nearly allied to it in structure, 

 several of which being found on our own coasts have afforded 

 opportunities for more accurate observation. These, as far as 

 their habits have hitherto been traced, are all of them burrowers, 

 making their way to a considerable depth in the sand at various dis- 



