The examination of sections from some of Prof. Zalessky’s material lent to me by Dr Kidston enables me to confirm Zalessky’s description, though I am not convinced that the primary xylem-strands are exclusively endarch: in most of the primary groups the protoxylem is clearly on the inner edge, but in a few cases there may be a small amount of centripetal xylem present. The characters of _Mesopitys Tchihatcheffi_ may be summarised as follows: Annual rings well defined, varying considerably in breadth; the summer wood is represented by several rows of narrower tracheids (fig. 490, A). In the piece of stem shown in the figure the breadth of the wood from the flattened and crushed pith to the broken outer edge is 6 cm. The medullary rays are numerous, uniseriate, rarely 2 cells in breadth; the pits on the radial walls of the ray-cells, 7–10 in the field, are apparently simple, oval, and oblique: the rays are generally 3–4 cells in depth but may be deeper. There are 1–3 rows of hexagonal alternate rows of pits on the radial walls of the tracheids. The primary xylem consists of groups, varying in size and sometimes reduced to a very few elements, in contact with the secondary xylem, usually though probably not invariably endarch. In the two narrow radially elongated and partially destroyed primary strands shown in fig. 490, B, the protoxylem, _px_, is on the inner edge. The leaf-trace passes through the secondary wood as a single strand. In the section reproduced in fig. 490, A, the crushed and flattened pith measures 9 by 2 mm.; it consists of thin-walled parenchyma with a few scattered thicker-walled cells. [Illustration: Fig. 490. _Mesopitys Tchihatcheffi._ A, transverse section showing rings of growth in the wood. B, primary xylem with protoxylem, _px_, and the edge of the secondary xylem, _x²_. (Kidston collection, 2156.)] Nothing is known as to the structure of the cortical tissue or leaves. =Antarcticoxylon.= Seward.