JURASSIC PLANTS FROM CROMARTY AND SUTHERLAND, SCOTLAND. 888 
The specimen described by HrEr from Lower Cretaceous strata of Greenland as 
Phyllocladites rotundifolius*™ bears a close resemblance to Strobilites Milleri, but 
a more accurate drawing, published by Narnorst,t of HEEr’s type-specimen, which is 
referred by him to the genus Drepanolepis, largely destroys the impression of affinity 
to our fossil suggested by HrxEr’s figures. The organs described by the latter author 
as seeds are regarded by Naruorst as the thickened bases of sickle-shaped, 
leaf-like organs. Reference may also be made to a fossil figured by Dunxer{ from 
the Quadersandstein of Germany as a fruit-spike possibly belonging to the Dicoty- 
ledonous genus Credneria, which presents a fairly close resemblance to the Scotch 
specimen. 
Strobilites Milleri, though too imperfectly preserved to be diagnosed with any 
degree of certainty, may perhaps be best described as a lax spike of sessile seeds agree- 
ing closely in habit and in size with a megastrobilus of Podocarpus spicata. 
We have adopted the non-committal designation Strobilites§ in preference to 
Stachyotaxus, as the data are insufficient to justify the use of the latter name. 
Cedroxylon Hornet sp. nov. (PI. II. figs. 22-25; text-fig. 5, B-F.) 
This species is founded on a piece of stem, 5 cm. in diameter, from Helmsdale on 
the Sutherland coast, which was sent to one of us by Dr Horne from the collection 
of the Scotch Geological Survey. The specimen consists of a portion of the wood 
with three small knots on the exposed and irregularly fractured surface. In a 
transverse section 2 cm. in breadth from the centre to the edge at the broadest part, 
rings of growth are very clearly shown (fig. 25); these vary considerably in breadth ; 
in some of the rings there is a gradual decrease in the diameter of the tracheides 
extending through several rows, while in places the transition from spring to summer 
wood is much more abrupt and only three or four rows of tracheides are affected. 
Occasionally a band of narrower tracheides extends over only part of the circumference. 
The transverse section as a whole affords a striking illustration of spasmodic breaks 
and irregularities in the succession of seasonal periods, and furnishes clear evidence 
of climatic changes affecting the cambial activity. Similar irregularities in the 
breadth of the rings of growth and the occurrence of partial rings are described by 
Dr Barser in a Wealden species, Cupressinoxylon vectense.|| This author gives 
several references to similar instances of cambial vagaries in other types of coniferous 
wood.{ The pith consists of more or less spherical cells with intercellular spaces, 
and the perimedullary zone is composed of rather smaller elements. The wood 
consists almost exclusively of tracheides, but there are some parenchymatous xylem 
elements in vertical series (text-fig. 5, B). The bordered pits, approximately 20. 
in diameter, are usually in single rows, frequently separate (fig. 22), but occasionally 
* HUuER (75), p. 124, pl. xxxv. fig. 17. + NatHorst (97), p. 43, pl. vi. figs. 24, 25. 
} Dunxer (56), pl. xxxv. fig. 1. § ScuimpEeR and Movuesxor (44), p. 31. 
|| BARBER (98). | See also Srwarp (96). 
TRANS. ROY. SOC. EDIN., VOL. XLVIII., PART IV. (NO. 32). 130 
