1049 
Affinities of Sutcliffa . 
latter case they are separated from one another by a delicate cell-wall. 
Their size varies somewhat, the larger cells being usually found on the side 
nearest the fibrous strands. The elements in question are precisely similar 
in appearance to those described and figured by Scott in S', insignis (p. 58, 
PI. IX, Figs. 14 and 15, and PL X, Fig. 22) and by Seward 1 as occurring in 
X. Williamsoni (p. 211, and PL XIII, Figs. 6, 7, 8, 11, and 12). Seward in 
his fossil described various stages in the organization of these elements, and 
concluded that * the characteristic receptacles which accompany the vascular 
bundles of Rachiopteris Williamsoni are of the nature of small secretory 
Text-FIG. 15. Transverse section of a unilateral leaf-trace bundle, x 55. xy\ — primary 
xylem ; p.xy. = protoxylem ; fs. = fibrous strand ; c. — cortex ; s.c. — secretory element. (Com- 
pare with Scott’s S. insignis , PI. IX, Fig. 15.) 
canals, formed as the result of a schizolysigenous process. In one slide 
there is a solitary instance of a bundle-canal containing dark-coloured con- 
tents similar to that in the larger canals of the fundamental tissue, and 
possibly representing the remnants of secretion. 5 Scott, on the other hand, 
is ‘ inclined to regard the large elements of the phloem as sieve-tubes 5 , and 
expresses some doubt as to ‘ the interpretation of these structures as 
developing canals \ In the new specimen the ring of small cells surrounding 
the scattered elements, which shows so clearly in S. insignis , does not 
usually occur, but the large elements sometimes show in the interior 
evidence of broken-down walls, giving the impression that the ring of small 
1 Seward, loc. cit. 
3 z 
