17 



is examined ; but when its internal surface is viewed, it is mostly ob- 

 scured by the double line which passes immediately across it. Upon 

 showing this curious tissue to my friend Mr. Edwin Quekett, he kind- 

 ly favoured me with some thin longitudinal slices from a stem of Piper 

 nigrum, in the vessels of which he said he had observed a tissue of 

 an exceedingly similar nature. Upon comparing these with the fossil 

 specimens, the tissues appeared to be precisely of the same construc- 

 tion, the only observable difference being that in the vessels of the re- 

 cent wood the dots and the double lines were more minute than in 

 the fossil tissue. 



There is very little doubt, therefore, that our fossil is either a true 

 Piper, or very nearly allied to that genus ; and this is rendered the 

 more probable from my having found several specimens of fossil 

 fruits from the Isle of Sheppey, which bear a striking resemblance to 

 those of some of the existing species of the Piper tribe. 



There is another remarkable circumstance attending the examina- 

 tion of this fossil wood. Some of the vessels contain large vesicular 

 globules, which appear to have been floating freely within their pari- 

 etes, (PI. ii. fig. 3 — 5) ; when not in contact with each other they are 

 perfectly globular and uncompressed : they vary very considerably in 

 size, in some cases filling nearly the whole diameter of the vessel. 

 The structure of which these globular bodies is formed is thin and ve- 

 ry pellucid, and no fibre or other organic structure is apparent upon its 

 surface. There are also, in some of the vessels, exceedingly small 

 vesicles interspersed among the larger ones, (PI. ii. fig. 3 a) ; a portion 

 of these are opaque and black, but the greater number of them are 

 transparent like the larger ones. These very minute vesicles do not 

 exceed the globules of circulation in Vallisneria in size ; and as we 

 find vesicles of every size intermediate between these minute ones and 

 the largest of the vesicles, it appears probable that the whole of them 

 may be attributed to a more than ordinary development of the glo- 

 bules of circulation, analogous to those observed tn Vallisneria and 

 other plants. 



I have never seen this curious fonn of tissue in any other wood, 

 either recent or fossil, but I have occasionally observed similar large 

 pellucid globules slowly moving in the great central cavity of the stem 

 of Chara translucens, while the circulation of the smaller globules 

 in its parietes has been proceeding with a much greater degree of 

 rapidity. 



Where the lapidary's process has removed portions of the larger ve- 

 sicles, as represented at b, fig. 3, 4, pi. ii, there is a granulated appear- 



TRANS. MIC. SOC. VOL. I. C 



