20 DESCRIPTIVE CATALOG II 



raens in the Museum, V. 13081 lacks the most noticeable 

 characters of the derived fossils, and might reasonably be 

 regarded as a true Lower Greensand fossil. There is also one 

 very fragmentary specimen from Ireland. 



48047. A narrow slice of a petrified specimen, partly polished. 

 The preservation of the tissues is imperfect, but indi- 

 cations of the solenosteles are visible, as well as the 

 numerous small lacunce of the rootlets. '* Greensand ; " 

 Potton. Purchased, 1871. 



48047 a. MiYroscopic sections of the above. T\vo narrow 

 transverse sections are mounted together on the same 

 elide. With a very low power the general character* 

 of a 7V///>N/.\w are visible, but the- actual cellular 

 tissue is almost entirely destroyed in the process of 

 petrifaction, and none of the finer d tained. 



Small concretionary /.ones, with black or yellow cen- 

 tres, mark the outline and position of the numerous 

 rootlets. In a single case the xylem of a rootlet cm 

 be made out, and this bundle appears to contain six 

 undoubted tra>'hei Is, one of which looks like an 

 exarch protoxyh in element ; beside tho uncrushed 

 cells are others, which may also have been vascular 

 elements. It is not jMMsihle to determine whether 

 or no the rootlet was diarch, but, so far -is its tissue is 

 preserved, it harmonises wilh the view that the root- 

 lets were all diarch in this genus. 



On the other piece of the section, towards the 

 middle, there is a small part of the solenostele of a 

 stem which has its wood sufficiently well preserved 

 for recognition. The stem lies at the edge of the 

 section, so that rather less than half of the arc of the 

 solenostele is included. The curve of the wood is 

 unbroken, and the band of tracheal elements is massive 

 (about 9 cells thick), so that presumably it was not 

 from that region of the stem which was giving off 

 leaves (c/. Kidston & Gwynne Vaughan's account 

 of T. Rossica}. Interspersed among the tracheids 

 (which have fairly thick walls and empty lumina^ 

 are crushed fragmentary elements, which probably 



