250 



Scientific Proceedings^ Royal Dublin Society. 



Pteridosperms or Oycadofilices. It is fern -like in habit, and in some of its 

 anatomical features, but is Gymnospermous in others (mesarch xylem, 

 bordered pits, secondary thickening in stem and roots). Heterangium is 

 recorded from Bear Island (?), Scotland, England, France, Germany, and 

 now from Ireland. It extends from the Upper Devonian, through the 

 Carboniferous to the Permian strata, but always, as hitherto described, in a 

 sterile state. Hence I examined with peculiar interest our Irish specimen. 



It is the carbonaceous impression of a piece of stem and attached leaf- 

 stalks. It is 14 cm. long, and 1 cm. wide in the internodes, and shows some 

 three leaf-stalks spirally arranged. No 

 specimen of Heterangium has ever been 

 found showing the stem, leaf-stalk, and 

 leaf-blade all in connexion. Further, the 

 leaf-stalk is naked from its base upwards 

 for at least 20 cm. of its length. Stur gives 

 a figure of a leaf-scar, and considered the 

 leaves of Heterangium deciduous like those 

 of Acrostiehum among modern ferns. In 

 the Irish specimen the lamina is unrepre- 

 sented. The sclerotic plates are well pre- 

 served as cross-strise, both in stem and 

 leaf-stalk. The wings of the stem formed 

 by the decurrent leaf-bases are well indi- 

 cated at the nodes. In H. Grievii the 

 leaf-trace is found to be occasionally, in 

 H. lomaxii regularly double. The leaf- 

 stalk of our specimen presents a feature I 

 cannot find described in any other Hete- 

 rangium. From the under side of each ^ig- l-— Reduced figure of E. hibemicum, 

 . , ... ,- ,1 • showing the spur-like appendages (a) of 



petiole near its insertion there arises a ij^ rachis. 

 spur-like outgrowth, showing signs of 



bifurcation. This abaxial basal appendage may be the proximal part of a 

 sporangiophore as suggested by the similarly placed one of Cephalopteris 

 mirabilis. Its presence, in association with other minor points of difference, 

 prevents me from identifying our specimen with H. Grievii ; and I propose to 

 call it accordingly H. Mbernicum ' — a specific name which will serve also to 

 indicate its origin. (PL XXI.) 



' Baily's fig. 2 represents, I think, {a) the branching rachis, (b) the stem with petioles of Heteran- 

 gium. I have at the same time satisfied myself from inspection of specimens that all Baily's "linear 



plants" are not referable to Heteranqium. 



