18.55.] HOOKER — FOLLICULITES MINUTULUS. .569 



blunt, opaque, prominent cones that stand out from the surface of the 

 membrane. The cell-wall is marked with very faint oblique lines, 

 appearing more like undulations of the cell-wall than a thickening of 

 it or deposit on it. Under a very high magnifying power, the lines 

 marking the junction of the contiguous cell-walls have a beautifully 

 beaded appearance (fig. 8). 



Beneath this investing coat of the cavity I occasionally found 

 broken pieces of tissue, represented by figs. 9-13, which approach 

 vascular tissue in character. 



The attachment of the sporular sac is by a broad base, that adheres 

 to the somewhat excavated base of the cavity of the sporangium ; the 

 apex of the sporular sac is drawn out into a very fine point, which 

 projects into the tubular canal at the apex of the sporangium, and is 

 there united to the cellular tissue lining the latter. The sporular sac 

 finally becomes retracted from this canal, and tears away a portion of 

 its lining membrane with it (fig. 5). 



The substance of the sporular sac is extremely delicate, but firm 

 and brittle, transparent and glassy ; it does not expand in water like 

 that of Rhytidosporum *, but is dissolved in hot nitric acid, and pre- 

 sents no action with iodine. 



The very different-looking cellular tissues figured are all evidently 

 referable to one type, but they may have belonged to more than one 

 layer. Some of the longer (fig. 10-13) approach vascular tissue in 

 character ; but I was quite unable to detect any stronger evidence of 

 vascular tissue, which, however, may very well be supposed to exist 

 along the edge of the fossil opposite the suture. 



The sporular sac, in its origin, insertion, membranous nature, &c., 

 closely resembles that of Carpolithes ovulum, but differs in many 

 remarkable points of form and anatomy ; thus it bursts by a minute 

 oblong slit below the narrow sharp apex, and appears to be formed of 

 but one layer of very compressed cellular tissue. Under a very high 

 magnifying power (^^^ lin. doublet, or i inch object-glass), this tissue 

 presents the same beautiful appearance that the lining membrane of 

 the sporangium does, the boundary-lines between the cells being 

 formed of strings of minute spherical bodies of various diameters, 

 and the intermediate membrane is either transversely undulated, or 

 appears so from the presence of excessively fine, parallel, waved lines. 

 What I have regarded as spores were the only contents of the sac in 

 one of the specimens, and consisted of a mass of extremely minute 

 spherical or oblong transparent bodies, of various sizes. In the other 

 specimens the sac was perfect ; but its cavity, and that of the sporan- 

 gium, were filled with fine silt, amongst which I could detect no 

 definite remains of vegetable tissue. 



With regard to the affinities of this fossil it is exceedingly difficult 

 to speak. The sporular sac at once suggests an alliance with Mosses, 

 and the traces of vascular tissue in Carpolithes ovulum, to which it may 

 be assumed to be allied, with Ferns. There are, however, very grave 

 objections to these affinities for either of the fossils. Thus, as regards 



* See above, p. 564. 



