Johnson — A Seed-hearing Irish Pteridosperm. 7 



Calymmatotheca fertile rachis and the Lagenostoma seed, for which we are 

 prepared by the researches already mentioned. Such organic continuity of 

 seed with parent; plant was first observed in a Pteridosperm by Kidston 

 in 1904 in Neuropteris heterophylla, 19U3 being the year in wliich the first 

 Pteridosperm seed — Lagenostoma — was identified as such. 



The photograph in Plate I., fig. 1, represents the impression of the seed- 

 bearing specimen in the Greological Survey collection, little less than natural 

 size (!■). The main stalk or stem/ 1 cm. in width, shows beautifully (fig. 2) 

 the sclerotic network cliaraoteristic of L. oldhamium, as well as the spinous 

 emergences. The bifurcated raohis is readily recognizable. This is so 

 general in tliese Carboniferous "Ferns" as to lose all generic value. 

 (The genus JDiplotmema founded by Stur to include forms with bifurcated 

 rachis is unnatural.) The foliage is typical of 8. H'diiinghami (Plate I., 

 fig. 1), showing the pinnules with lobed conchoidal, rounded segments, and 

 branched, diverging, non-parallel venation. The hooked emergences are 

 visible on the rachis, and appear on tlie pinnule segments (Plate II., 

 fig. 4) as small bosses or tubercles. The rounded form of the pinnule 

 segments of 8. Hdiiinghausi is of some interest. On looking over a 

 large number of species of 8phenoptem, it is possible to divide them 

 into two main series. In the one represented by " 8. Hdiiinghausi," the 

 pinnule segments have a more or less rounded outline, and their branching 

 veins diverge from one another, and from the main vein whicii forms 

 a sort of midrib to the segment. In the otlier series, represented by 8. elegans, 

 the pinnule segments are not rounded in outline. They are wedge-shaped or 

 roughly comparable to an inverted isosceles triangle, of which, in some forms, 

 the base is very narrow. Tiie veins of tiie pinnule segment, with or without 

 bifurcation, do not, however, diverge widely from one another, but run parallel 

 or sub-parallel to one another. In tlie 8. Hminghausi series the rounded 

 segments sliow pinnate diverging venation, and in the 8. elegans the cuneiform 

 segments show dichotomous or bifurcated sub-parallel venation. The impor- 

 tance of this distinction is illustrated in Lotsy's valuable " Vortrage liber 

 botanisehe Stamniesgeschichte," where fig. 499 (page 708), an illustration 

 (after Potonie) of 8. Hdiiinghausi, shows the more or less triangular or 

 cuneiform pinnule segments of the 8. elegans type, and is recognizable 

 by the transverse strise of the rachis observable in tlie figure, as actually 8. 

 elegans — i.e. Heterangium Grievii, Willm., anotlier and earlier Pteridosperm. 



1 am well aware of the possible pitfall in using venation as a test of 

 aflBnity ; but it is of interest to note that the subparallel dicliotomous type 



' Though the impression iudicates by its characters that this is a piece of the stem, it must be 

 remembered that the chief rachis hasbeeu fuimd 3 cm. wide, aud the whole lea£ 2 to 3 m. long. 



