l72 Scientific Proceedings, Royal Dublin Society. 



and does not make its appeai'ance in any Dicotyledou or Monocotyledon. Its 

 venation is different from that of any recent ferns, even from suggestive 

 forms like Actiniopteris (9) and Aneimia. Hence its venation is of 

 considerable taxonomie value as a guide to palseobotanists in tracing the 

 genus through time. 



Interesting as is the deposit of fossil plants in tlie Upper Devonian beds 

 of Kiltorcan, no signs of Gymnosperms have hitherto been observed there. 

 It is a surprising fact that, whether due to absence of the fossil, or to 

 insufficiency of exploration, there are no fossil Gymnosperms recorded for 

 Ireland, except a few from the basaltic Miocene deposits of Co. Antrim, and a 

 Sternbergia or Artisia, the pith-cast of the stem of Cordaites, from the Yellow 

 Sandstone and Coal-Measure deposits of Cultra, Co. Down. When recently 

 examining in detail a large quantity of material quarried for me tliis year, 

 partly through the aid of the Eoyal Dublin Society, I was surprised to find 

 in faint outline on one slab an impression which closer examination and 

 magnification satisfied me was different from any type of fossil I had yet 

 seen in these rocks. 



A general idea of this discovery is obtainable from the illustrations, 

 (PI. X, figs. 1 and 2). 



The leaf (or leaflet) is 7 cm. long, 5 cm. wide, is in general outline fan- 

 shaped, and gradually tapers to form a ribbon-like petiole, 25 mm. long, 

 2-5 mm. wide. It is thus in general form Psygmophyllum-like. The 

 impression in the rock is incomplete on one side (the left as looked at). 

 Enough of it is, however, preserved to show that the leaf-blade was symmetri- 

 cally and deeply divided into two lobes, and each of these again into two, 

 themselves sub-divided, ribbon-like segments. The whole lamina is more 

 or less palmately lobed, giving eight lobes in all. Its venation is clearly 

 dichotomous. The petiole is traversed by four veins in its upper part, and, 

 judging from tlie formation of these by the fusions of the veins from the 

 lamina, these four, though lost in the impression of the basal part of the 

 petiole, fuse in pairs, and form the double leaf -trace, so characteristic of 

 Ginkgo and primitive Gymnosperms. It would be going too far to assert 

 that this Ginkgophyllum possesses the double-leaf trace. The venation of 

 Oinkgophyllum kiltorkense agrees, as far as traceable, with that of G. biloha. 

 We have thus, persisting from the Devonian epoch to the present day, a 

 Ginkgo type of megaphyllous leaf as interesting as is the microphyllous 

 Equisetum withiu its range. 



There is another feature in the venation of the Ginkgoaoese to which I 

 wish to direct special attention, as it seems to me to have a distinct bearing 

 on the degree or depth of segmentation or lobation to which a lamina may 



