564 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 13, 



the internal sac is formed is also peculiar, for they gradually diminish 

 in size towards the terminal pore, and evidently indicate that the 

 latter performs some important office. 



The spores themselves are very numerous, thouf>;h the sac was 

 not at all full of them. The Rev. Mr. Berkeley, to whom I showed 

 them in situ, and who most carefully went over my analysis, was 

 quite unable to suggest any other explanation of their origin than 

 that they really were the reproductive organs of the fossil ; though 

 equally impressed with myself by the pheenogamic character of the 

 whole, and quite unable to compare the spores with those of any 

 cryptogamic plant known to him. 



From the opacity and brittleness of the walls of the sporangium, 

 I was unable to obtain good sections at all points ; but it seems to 

 consist chiefly of a dense, compact cellular tissue, traversed on one 

 side (where there is an evident thickening) by a bundle of vessels 

 l)assing from the base to the terminal mamilla. The cells of the 

 outer surface are denser, and have thicker walls, than those of the 

 imier, and are further perforated by canals passing from cell to cell ; 

 the prominence of these cells gives the outer surface its reticulated 

 appearance. The inner surface again is lined with much larger, ob- 

 long, hexagonal cells, with short transverse bars on their walls. The 

 scalariform vessels of the vascular bundle closely resemble spiral 

 vessels, but arc not in a sufficiently perfect state for an accurate 

 analysis ; they are accompanied by fusiform cells, and tubes, ap- 

 parently of pleurenchyma. The elevated disc surrounding the 

 base of the terminal mamilla is irregular in outline, and may be the 

 remains of a membrane that once covered the apical pore ; the ma- 

 milla itself appears to be composed of but one stratum of cells, but 

 tliis is doubtful. 



The sporular sac is a singularly beautiful structure, being as trans- 

 parent, and apparently as })erfect, as when fresh, absorbing moisture 

 and expanding under it ; it is soluble in boiling nitric acid, but I 

 tailed to produce any reaction upon it or upon the spores with iodine 

 or sulphuric acid. It is easily ruptured, and appears to be formed 

 of two layers of excessively delicate cellular tissue, whose areolae are 

 not conformable to one another, except at the apex of the sac ; the 

 latter is conical, and no doubt once occupied the cavity of the ma- 

 milla of the sporangium, from which it has become retracted after 

 the dispersion of the majority of the spores, and the consequent col- 

 lapse of its walls. 



The spores are amber- coloured, and the depressed central areola is 

 sometimes occupied by an opaque or transparent mass : the delicate 

 radiating striae on the wedge-shaped sporules have suggested the 

 generic name of Bhytidosporum^, should it be found advisable, 

 when the structure of other Carpolithesf is better known, to separate 

 this from them. 



Except for the presence of the spores in the sac of this specimen, 



* From Gr. puriv, a wrinkle, and airopov, a spore. 



t As at present lin)ited, Carpolithes is an artificial assemblage of organs of 

 fructification. 



