•~>0 MB ROBERT KIDSTON ON 



granulated (fig. lc). These granular roughnesses measure about 0*20 mm.,* and are 

 covered by a thin cellular envelope, the size of the cells forming this layer being such 

 that from three to four cells equal the size of the individual granular roughnesses. The 

 cells are therefore about O'Oo mm. in their longest diameter (pi. ii. fig. Id). 



Some of these larger sporangia are seen in side view on pi, i. fig. Id d'. 



On the exposed surface of some of the bases of these larger upper bracts is a sub- 

 rhomboidal mark with a central point, and below it the indication of a semicircular 

 .iica (fig. lb). This may represent the point of attachment of the bract to the axis of 

 the cone, but of this T am not certain, as it might perhaps represent the part where 

 dehiscence took place. This structure is well seen on fig. 1 at e and b. 



It is from the examination of this specimen that I have come to the conclusion that 

 most probably the cones of Sigillaria were heterosporous, for I do not see what other 

 explanation can be given than that the granular structure is caused by contained 

 microspores covered by a delicate cellular envelope. I do not claim for this interpreta- 

 tion of the fossil an absolute certainty, but dealing with bodies so minute as microspores! 

 jut served in the manner of the specimen under discussion, I scarcely see how we can 

 expect more conclusive evidence. This interesting specimen, which occurs on a small 

 slab with a piece of the bark of Sigillaria camptotcenia, Wood, sp. (but whose association 

 may be merely accidental), was collected by Mr John Rorrison from the " Major Coal," 

 at Xo. 3 Pit, Springhill, Crosshouse, Ayrshire (Lower Coal Measures), and communicated 

 to me by the Rev. D. Landsborough, Kilmarnock, to both of whom I am much 

 indebted. 



Sigillariostrobus rhombibractiatus, Kidston, n. sp. 



PI. I. figs. 1-8; PI. II. figs. 10-11. 



Cone cylindrical, elongated, stalked, caducous, apex blunt ; bracts caducous, rhom- 

 boidal, single-nerved, with an acuminate point, finely ciliate on margin, placed spirally 

 on axis. Pedicel without ribs, bearing distant lanceolate bract-like leaves, which 

 become more numerous at the base of the cone, round which they are closely placed ; 

 pedieel thickly covered with small acicular points. Macrospores large, rough, with small 

 apiculi, and having a triradiate ridge on lower surface, 1*5 mm. to 2 mm. in diameter. 



Remarks. — This species is represented by over a dozen specimens from Monckton 

 .Main Colliery, all of which have been collected by Mr Hemingway. Of these the more 

 interesting examples are here figured and described. 



* If I am correct in regarding the cause of these " roughnesses " to be contained microspores — pre- 

 amably tiny were still united in groups of four, as is frequently seen in the cones of Lepidostrobus — then the 

 r/ ■ of the individual microspores would be less than 0*10, for the thickness of the containing envelope adds to 

 their apparent size. 



t Tin' *iy>- of th<- microspores in a cone of Lepidostrobus Bhowing structure is O02 mm. 



