ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 675 



The sieve-tubes of the Hymenophyllacese and Schizaeacere do not 

 appear to form callus ; but in other respects (perhaps excepting Schizaea) 

 agree structurally with the sieve-tuhes of other ferns. Silica-nodules 

 occur in the cavities of parenchyme-cells in some species of Lygodium 

 and Anemia. The fibres in the petiolar bundle of some species of 

 Lygodium, Schizaea, and Anemia are to be regarded as modified sieve- 

 tubes. Those of Trichomanes Prieurii, on the other hand, appear to be 

 formed either all from parenchyme or some from parenchyme and some 

 from sieve-tubes. The species of Lygodium are very uniform in struc- 

 ture, and possess a solid stele ; Schizaea has a medullated stele ; while 

 dialystelic structure is found in Mohria and some species of Anemia, 

 solenostelic structure in others. The " seedling " [sporeling, Ed.] of 

 Lygodium does not suggest reduction from a more complicated type. In 

 the " seedling " of Anemia the solid stele is converted into a dialystelic 

 one by gradations similar in type to those found in Pteris. The proto- 

 xylem belonging to the stem in SchizseaceaB is scattered, does not include 

 spiral elements, and is differentiated mostly with no relation to the leaf- 

 traces. The petiole possesses a single bundle. The roots appear to be 

 diarch throughout. 



Muscinese. 



Anatomy of the Leucobryacese.* — From the anatomical characters 

 of the leaves, J. Cardot classifies the genera of Leucobryaceaa in four 

 sections, viz.: — (1) Leucobryese ; leaf-vein without a bundle of stereid 

 cells; chlorocysts (chlorophyll-cells) tetragonal on transverse section, 

 in a single row along the entire length of the veiu (Leucobryum, Ochro- 

 bryum, Schistomilrium, Cladopodanthus. (2) Leucophaneaa ; leaf-vein with 

 a bundle of stereid cells in the middle, chlorocysts tetragonal on trans- 

 verse section, in a single row through the entire length of the vein 

 (Leucophanes). (3) Octoblephareae ; leaf-nerve without a bundle of 

 stereid cells, chlorocysts triangular on transverse section, in a single 

 row through the entire length of the vein (Cardotia, Octoblepharum). 

 (4) Arthrocormeaa ; leaf-vein without a bundle of stereid cells, chloro- 

 cysts irregularly arranged in three rows, at least in the upper part of 

 the vein (Arthrocormus, Exodictyon). The author regards the whole of 

 that portion of the leaf which consists of several layers as a vein ; the 

 lamina including only the marginal portion of the leaf which is only 

 a few cells in width. The vein may consist of the same number of 

 layers of cells throughout (usually three), or the number of rows may 

 gradually diminish towards the apex. 



Alg-86. 



Melobesiese.f — M. Foslie gives a monograph of the species hitherto 

 known of this section of the Corallinacese. The characters used for 

 discriminating the genera and sub-genera are mostly derived from the 

 reproductive rather than from the vegetative organs. The genera are 

 ten in number, viz.: — Archeeolithothamnion (Rothpl.) Fosl. (13 sp.), 



* Mem. couron. par l'Acad. Sci. Cherbourg, 1900, 84 pp. and 19 pis. See Bot. 

 Centralbl., lxxxvii. (1901) p. 167. 



t Kgl. norsk. Vidensk. Skrift., 1900, No. 5, pp. 1-22. See Bot. Centralbl., 

 lxxxvii. (1901) p. 49. Cf. this Journal, 1897, p. 417. 



