Johnson — Is Archceopieris a Pteridosperm ? 121 



care in the Botauieal Division of the National Museum in Dublin, as well as 

 those in the collection of the Geological Survey of Ireland, and a small 

 collection preserved in the Geological Division of the Royal College of Science, 

 Dublin, made a few years ago in the course of an exploration of the Kiltorean 

 beds by Professors Carpenter and Swain in search of fossil Isopods. I have 

 not, as yet, been able to visit the fossil locality. It will be convenient if I 

 first of all give an account of my examination of the Dublin specimens of 

 Arehceopteris /libeniica, calling attention to any new features described : — 



1. Frond (PL lY.)- — The frond, the only part of the plant known, is either 

 wholly vegetative, or partly vegetative and partly fertile. It is bipinnate and, 

 broadly ovate-lanceolate in shape, and of great size. A specimen, 5 feet long, 

 was seen by Baily in the rock at Kiltorean. The largest one on exhibition in 

 the National Museum, Dublin, is nearly 3 feet long. 



2. Bachis (PL V., fig. 1). — The base of the rachis is expanded, 1-3 inches 

 wide and 3 inches long in its stipulate parts, somewhat concave on its adaxial 

 side, with some five ridges and alternating furrows. It is, in the Umbelliferous 

 sense, a sheathing base ; but inasmuch as its wings may be slightly free at their 

 distal end, it is better, perhaps, to speak of the base as stipulate, and of the 

 stipules as adnate, as in Eosa. Each stipule is vascular. Kidston was 

 the first to describe the basal wings as stipules. Baily in his amended and 

 latest reference to Archceopieris hihernica, in his " Figures of Characteristic 

 British Fossils " (published in 1 875), speaks of and figures the " scaly base of 

 the frond." Between the lowest pair of pinnae and the stipules the rachis 

 is not naked, but clothed with lateral vascular outgrowths, which are not 

 scales or ramenta but vascular pinnules, reduced more or less. Tliey are not 

 spirally but distichously arranged. In one specimen I have counted eight 

 pairs of them, and yet in another they are scarcely observable. They are 

 sometimes exposed in the rock edgewise, and are rarely seen as clearly as 

 in fig. 1, Plate V. The stipules and these paired appendages are all of 

 the same texture, and, if it were allowable, it might be more indicative of 

 their relationship to one another to speak of tlie basal expansions on either 

 side of the rachis, below the lowest pair of pinnae, as a whole, as " interrupted" 

 stipules. The bearing of this mode of designation will be more obvious 

 later. The racliis proper is well developed; and, judging from some of the 

 impressions, was convex on its under and slightly concave on its upper side. 

 There is clear indication of a longitudinal striation with slightly raised ridges 

 and furrows. In addition to this, there is a transverse or horizontal striation, 

 which is distinct from any such puckering, blistering, or other surface-markings 

 as might be due to the mode of preservation in tlie fine sandstone. The 

 rachis was apparently traversed lengthwise by numerous vascular bundles 



SOIENT. PKOC. K.D.S., VOL. XIH., NO. VIH. T 



