196 Note . 
externally and lined internally with soft tissue, while the nucellus stands freely up into 
the seed cavity. 
Scott and Maslen ascribe most of the British petrifactions of this genus to 
Trigonocarpus Parkinsom , Brongniart. They include under this species the seeds 
described by Hooker and Binney without a specific name, and by Williamson 1 under 
the name of Trigonocarpon olivaeforme, L. and H. A comparison of the seed, which is the 
subject of the present note, with typical examples of T. Parkinsoni , with especial 
reference to the measurements and figures in Scott and Maslen’s paper, leads to the 
conclusion that, though our specimen shows a general similarity to T. Parkinsoni , and 
is of about the diameter of a large specimen of this species, yet its seed body is 
distinctly shorter. The form is thus more rounded and less oval. The sclerotesta at 
the base of the micropylar canal shows, also, a greater increase in thickness than is 
usually to be noticed in T\ \ Parkinsoni. The new specimen, on the other hand, bears 
a very close resemblance in its dimensions to one of the petrifactions figured by 
Hooker and Binney . 2 An ‘ impression’ of Carpolithes alata ( Trigonocarpus Par- 
kinsoni ?) from Jarrow, described by Scott and Maslen , 3 though somewhat larger than 
the specimen under discussion, resembles it closely in proportions. It is probable 
that this impression, together with Hooker and Binney’s section to which reference 
has just been made, and the petrifaction described in the present note, may prove 
eventually to belong to a distinct species. 
AGNES ARBER. 
Sedgwick Museum, Cambridge. 
1 Williamson, W. C. : On the Organization of the Fossil Plants of the Coal-measures. Part 
VIII. Phil. Trans. Roy. Soc. London, vol. 167, 1877, pp. 248, &c. 
2 Hooker, J. D., and Binney, E. W. : loc. cit., PI. IV, Fig. 7. The figured slide is preserved 
in the British Museum, Nat. Hist. Gen. Coll., S. 3529. 
8 Scott, D. H., and Maslen, A. J. : loc. cit., p. 130, and PI. XIII, Fig. 18. 
