ON NEMATOPHYTON AND ALLIES. 43 



we have now proved these to be part of the normal structure. All the cells show a well- 

 rounded form and sharp outline, with none of the breaking down which would at once 

 appear in a decayed tissue. We are, therefore, justified in the conclusion that the struc- 

 ture of Prototaxites is wholly normal. 



From the foregoing facts, we are justified in the following conclusions : — 



1st. The plant is not vascular, and the appearance of rings is independent of the 

 causes which determine the layers of growth in cxogens. 



That the plants were of very considerable size, must be admitted, since specimens 

 have been foiind having a diameter of eighteen inches,' and this implies a very consider- 

 able height. It is also true that rings dependent upon structural variations are also 

 present, but the relations which the more and less dense portions bear to one another, 

 show that they are not true growth rings, and, at most, represent only a pseudo-exogenous 

 growth. The possibility of such size and mode of growth, even among Algse, has already 

 been pointed out by Mr. Carruthers.^ Moreover, we have proved, not only the absence 

 of a proper vascular structure, but the absence of a pith and medullary rays as well. 

 From this latter fact, it is clear that there could have been no external structure difi'ering 

 very materially from the internal ; wherefore we conclude that — 



2nd. The plant was possessed of no true bark. The tissue was of the same kind 

 throughout, and whatever cortical layer may have been present, was in all probability 

 only a superficial modification of that composing the general structure. 



3rd. An intimate relation exists between the large tubular cells and the myceloid 

 filaments, the latter being a system of small branches from the former ; the branching- 

 being determiined chiefly in special open areas which simulate medullary rays. The 

 relation here shown was susj)ected by Mr. Carruthers, although, from the sections 

 examined by him, he was unable to establish the fact.^ The distinct branching of the 

 larger cells, and their peculiar relation to the open radial areas, can, however, hardly 

 be interpreted in any other way. 



4th. The specimens examined exhibit no evidence of special decay, and the struc- 

 ture throughout is of a normal character. 



We arc now brought to a consideration of our final and most important conclusion, 

 viz., the affinities of the plant. The absence of structural markings, of vascular and 

 fundamental tissue, as well also of a cortex, together with the branching and non-septate 

 character of the cells — all show conclusively that there can be no affinity with vascular 

 plants, much less with the Gymnosperms, in consequence of which the name Prototaxites 

 loses its value. 



Mr. Etheridge has pointed out the occurrence, in N. Hicksii, of an occasional fine 

 striation.^ This marking we have also noted in the case of at least two cells of this spe- 

 cies, b^^t, from the condition of preservation, which all the material so far examined ex- 

 hibits, together with the fact that no similar marking has been seen in either of the other 

 two species brought to our notice, leads us to question if it represents actual structure in 

 the cell wall itself N. Hicksii is found only in the form of small fragments, which 

 strongly suggest the action of the waves in breaking up the half-dried plants as they 



' Geol. Surv. Can., Fossil Plants, 1871, 17. -M. Mic. Jn'l, viii, 170. 



3 M. Mic. Jn'l, viii, 169. • Quart. Jn'l Geolog. Soc, Aug. 1881, 492; fig. 4. 



