Linnaan Society, 495 



It is a curious fact that the whole of the specimens of this species 

 collected by Mr. Cuming have the lower portion of the lip broken 

 away. 



MiTRA ciTRiNA. Mitv. tcstd ovato-conicd, superne rotundatd, solidi- 

 usculdy spird hrevi, apicem versus suhtiUter sulcatd, apice elato, 

 acuto ; lavigatd, aurantio-citrind, livido-castaneo varie tinctd ; co^ 

 lumelld quinqueplicatd ; aperturd longissimd. 

 Conch. Icon., Mitra, pi. 27. f. 215 a and h. 



Hob, ? 



A new and very remarkable Cone-like species,. in the collection of 

 Thomas Lombe Taylor, Esq., of Starston, Norfolk. 



LINN^AN SOCIETY. 



March 18, 1845.— E. Forster, Esq., V.P., in the Chair. 



Read *' Remarks on the Examination of some Fossil Woods which 

 tend to elucidate the structure of certain tissues in the recent Plant." 

 By Edwin John Quekett, Esq., F.L.S. &c. &c. 



The structures which Mr. Quekett proposes to elucidate are the 

 fibres of spiral vessels and the dots of the woody fibres of Conifercd. 



On the first head he states, that in the examination of a specimen 

 of fossil Palm- wood, he observed that a portion of it readily broke 

 down into minute fragments, which, on examination under the mi- 

 croscope, were seen to be composed of cylinders more or less elon- 

 gated and minute rounded granules. Round the cylinders was wound 

 a perfect screw (with either a single or compound helix) undoubt- 

 edly fashioned from the interior of the spiral vessel, and affording 

 the most satisfactory evidence that the spiral fibre is really formed 

 in the interior of the vessel, as most recent observers have main- 

 tained. 



On the second point, the nature of the dots on the woody fibres 

 of Coniferce, Mr. Quekett's observations derived from fossils also 

 confirm the views now most generally entertained by microscopic 

 observers of the recent structures. In a specimen of fossil wood from 

 Fredericsberg in Virginia, received from Prof. Bailey, which was 

 easily broken into minute fragments in the direction of the woody 

 fibres, he found a beautiful example of casts of woody tissue with 

 numerous spirals traversing the interior. At various parts were seen 

 arranged the ordinary coniferous dots, to the outside of which (pro- 

 jecting beyond the outline of the fibre when seen obliquely) adhered 

 small bodies of the same size which bore the precise representation 

 of the coniferous disc, and were evidently casts of cavities existing 

 in the original plant : some of these were also seen detached. These 

 appearances, Mr. Quekett states, prove the correctness of the mo- 

 dern belief, that the discs are formed by depressions on the outside 

 of the walls of two contiguous fibres, giving rise to cavities of a len- 

 ticular form. 



Mr. Quekett concludes his paper with some observations on the 

 process of silicification in its various stages and modifications ; and 



