OF LOWER GREENLAND PLANTS. 275 



is irregular and roughly pentagonal in shape, and is just 

 dividing in the transverse sections available (see text-fig. 82). 

 Primary wood is poorly preserved, arranged in an irregular ring, 

 and not in well-marked bundles. Secondary wood consists of a 

 solid mass of thick-walled fibres with little or no wood-paren- 

 chyma, and with the vessels lying evenly distributed in pairs, 

 sometimes in radial triplets, or isolated. The arrangement and 

 size of the vessels are very little affected by the growth-rings. 

 Tt/Joses occur in many of them. Growth-rings are much more 

 conspicuous to the naked eye than under the microscope. Their 

 limits are marked by a narrowing of two or three rows of fibre- 

 elements, rather than by the distribution or size of the vessels 

 (text-fig. 83). 



Medullary rays are principally uniseriate, a few are biseriate 

 or three cells wide. The cells appear to be uniform in character 

 save for slight variations in their radial elongation. The rays 

 range in height from about 6 to 40 cells, some of the biseriate 

 rays being a little higher. 



Brandling appears to have been frequent, several " knots " 

 are externally visible in the wood, and the remains of two 

 branches at least are seen in the transverse section (see text- 

 fig. 82). 



Phloem, cortex, and baric are unpreserved. 



DETAILS OF THE ELEMENTS. So far as can be judged from the 

 poor state of preservation, the majority of the elements of the 

 pith were thick-walled and pitted, roundish in outline, and with 

 small intercellular spaces. Among these are some stone-cells 

 with excessively thickened walls. The primary wood-elements 

 are small and too poorly preserved to describe in detail. The 

 secondary wood-vessels are roughly circular ; when two are ad- 

 jacent the walls of contact are nearly straight. They average 

 25-70 p in diameter, some being a little larger. The walls 

 appear to be very thick, but this may be petrifact. The pits in 

 the walls are just discernible, the details are not ascertainable 

 owing to the poor preservation. Wood-fibres are roughly 

 hexagonal, averaging 12-20 p in diameter. Their walls are 

 exceedingly thick and the lumen very small in most eases ; they 

 are pitted, but the nature of the pits is not clear. Wood- 

 parenchyma may be present in small quantities. I have not 

 been able to detect cells well enough preserved to be described. 



T2 



