[ 66. ] 



No. 8. 

 LIBOCEDRUS AND ITS CONE IN THE IRISH TERTIARY. 



By T. JOHNSON, D.Sc, E.L.S., 

 Professor of Botany, Royal College of Science for Ireland, 



AND 



JANE G. GILMORE, B.Sc. 

 (Plate IV.) 



[Read Junk 27. Piinted August 28, 1922.] 



The present paucity of Conifers in the Irish Flora (Tax us and Juniperus) is most 

 marked on comparing them with the extinct forms. We know that Pimis, 

 Sequoia, C'ri/ptomeria , and Cupresszts once flourished on the mountain slopes of N.-E. 

 Ireland. We propose to add to this list the genus Libocedrus. While Sequoia is 

 now coniined to West North America, Cryptomcria to Japan and East China, and 

 Cupressus has its nearest representative in the Mediterranean region, Libocedrus 

 has a much wider, though discontinuous, range, and is represented by eight species, 

 of which three occur in America, one in S.-E. China, and the rest in New 

 Zealand, New Caledonia, and New Guinea. It occurs to-day in much the same 

 localities as Sequoia and Cryptomena, but also ranges further southwards both in 

 the Old and New World. 



Mr. A. Ueane, the Curator of the Public Art Gallery and Museum, Belfast, 

 kindly lent us, for comparison with the flora of the Washing Bay Bore, the 

 collections of Irish Tertiary fossils. Among them we discovered two slabs with 

 cones and several slabs with foliage which came from the Interbasaltic beds of 

 Ballypalady. We believe these to be the cones and foliage of Libocedrus 

 salicornioides, Unger. 



The cone (PL IV, figs. 1, 2) is oval oblong, 6'5 x 3 mm., borne on a short lateral 

 shoot, and apparently shows two fertile scales at right angles to two sterile ones. 

 The oval cone of a living Libocedrus consists of four, rarely six, scales in pairs at 

 right angles. The outer lower pair is very short in L. decurrens. Each cone-scale 

 is sub-apically mucronate. This mucro represents the free tip of the carpel of 

 which the body is fused to the ovuliferous scale. In L. pilumosa (L. Doidana, 

 PI. IV, fig. 3) the sterile pair of scales is better developed than in L. decurrens, 

 and about one-third the length of the fertile pair, each scale having at its centre, 

 not sub-apically, a pronounced recurved mucro. Jn our fossil a fertile scale is 

 shown in surface view. The projection on the right may be either a sterile scale 

 at right angles to it or the mucro of such a scale of the same length as the fertile 

 one. If this latter view be accepted, L.plumosa would be intermediate in this 

 respect between L. decurrens and the fossil. In an attempt at restoration of 

 tissue we got scraps of wood showing bordered pits in the tracheid(Pl. IV, fig. 4) 

 and medullary rays with small pits (Pi. IV, fig. 5). As far as they go, these scraps 

 and one from a foliage shoot (PI. IV, fig. 7) agree with the structure of the living 

 Libocedrus viooA. 



