JURASSIC PLANTS FROM CROMARTY AND SUTHERLAND, SCOTLAND. 885 
tracheides ; the slightly oblique transverse walls are pitted, and partially bordered pits 
are scattered over the vertical walls (text-fig. 5, D). 
The value of anatomical features as criteria for the determination of fossil coniferous 
wood is exceedingly difficult to estimate, and even in the case of well-preserved material 
it is often impossible to speak with confidence as to generic position. In recent years 
considerable additions have been made to our knowledge of the anatomy of both recent 
and fossil conifers, particularly in regard to such diagnostic characters as the pitting of 
the medullary-ray cells, the distribution of xylem-parenchyma, the amount of variation 
in regard to the arrangement of pits on the walls of the tracheides, and other characters. 
The investigations of Dr Goran of Berlin, of Professor Jerrrey and his school, and of 
Professor LicnierR are especially noteworthy ; whatever views may be held as to the 
theoretical opinions based on structural features, the work accomplished by these 
observers has added considerably to the scientific possibilities of this difficult branch of 
palzeobotanical research. 
The features exhibited by the Helmsdale wood suggest comparison with the genus 
Cupressinoxylon of GorPPERT and with Cedroxylon Kraus, as emended by GotTHan.* 
The arrangement of the bordered pits on the tracheide-walls is of the type met with in 
both these genera,t but in the Abietineous pitting, that is, the occurrence of small pits 
on the vertical as well as on the horizontal walls of the medullary-ray cells, the Scotch 
wood agrees with the genera Cedroxylon and Pityoxylon and not with Cupressinoxylon. 
From the latter genus our specimen is distinguished by the absence of resin-canals, and 
it agrees with Cedroxylon in the limitation of the xylem-parenchyma to the summer 
wood, In the Arctic species of Cedroxylon described by Goran from King Charles 
Land the frequent occurrence of double alternate rows of bordered pits, as in Araucarian 
wood, is a distinguishing feature probably of specific rank. There is a slight tendency 
towards this arrangement in Cedroxylon Horne (fig. 22). The name Cedroxylon does 
not necessarily imply generic identity with Cedrus, but denotes affinity to such genera 
as Cedrus, Pseudolarix, and Tsuga.t 
Among other records of Cedroxylon, reference may be made to Cedroxylon 
barrennanum Fliche§ from the Lower Cretaceous rocks of the Haute-Marne, France ; 
Cedroxylon blevilleuse Lign. from the Gault of Normandy ;|| and to some imperfectly 
preserved specimens described by Drs Sroprs and Fusm as C. Matsumurx and C. 
Yendoi from the Upper Cretaceous rocks of Japan. In Licnier’s species the pits 
on the tracheides are relatively large, 13-20 in diameter, in this respect agreeing 
with those of the Helmsdale species (20); there is also the same stellate type of 
pitting on some of the tracheides as that shown in fig. 22. The two species C. 
* GorTHAN (05), p. 102. 
+ Barper (98) ; Gorman (08), pp. 23, 26. 
{ JErrrey (11), p. 25. 
§ FiicuE (00), p. 16, pl. ii. fig. 1. 
|| LienrER (07), pp. 263-267 ; pl. xviii. figs. 15-17, 21-23 ; pl. xxii. fig. 72; pl. xxiii. fig. 87. 
‘I Sropgs and Fusir (10), pp. 42-44; pl. iv. figs, 20-23 ; pl. iv. figs. 24-26. 
