660 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Lyginodendron and Heterangium.* — The late Prof. W. C. William- 
son and Dr. D. H. Scott discuss the structure and relationship of these 
fossil forms from the Coal-measures, which they regard as forming an 
intermediate link between the Vascular Cryptogams and the Cycadeae. 
In Heterangium the primary structure of the stem is much like that of a 
monostelic fern such as Gleichenia, while the leaf-trace bundles closely 
resemble the foliar bundles of a Cycad. In Lyginodendron the whole 
structure of the stem suggests a Cycad, but with the remarkable 
peculiarity that the bundles have the structure which in Cycadeae is 
usually limited to those of the leaf. Both genera have, in various re- 
spects, points in common with Gleicheniaceae, Osmundaceae, Marattiaceae,. 
Ophioglossaceae, and Cycadese. 
Muscineae. 
Dissemination of the Spores of Mosses.t — Prof. K. Goebel has 
studied the part taken by the peristome and by the columel in the 
dissemination of the spores in the various families of Musci. The- 
peristome may serve only for the hygroscopic closure of the capsule, or 
may also aid, with or without the assistance of the capsule, in securing 
the gradual escape of the spores. This may be effected, when the peri- 
stome is simple, either by its consist ng of long teeth which remain 
curved over the opening when dry, or by the teeth remaining united at 
their tips ; when the peristome is double, either by the opening being, 
partially closed by the inner peristome, or by the presence of elaters. 
The development of the peristome appears to have proceeded on 
different lines in the different families of mosses ; and to have undergone 
retrogression in some. This has taken place either when the number of 
spores in a capsule is very small, or when other contrivances are pro- 
vided for the dissemination of the spores, such as its violent bursting in 
Sphagnum; its splitting in Andresea ; the narrowing of the mouth in 
Physcomitrium ; or the formation of a basal opening in Phascum. The- 
columel assists in the dissemination of the spores in Tetraphis , where it 
takes part in the formation of the peristome-teeth ; in the Splachnaceae,, 
where it reduces the opening of the capsule ; and in the Polytrichaceae r 
where it forms the epiphragm. 
The author regards the sporogone of Nanomitrium as probably an 
archaic form. The capillary peristome of Dawsonia consists of rows of 
cells which have the same origin as the peristome-teeth of the Poly- 
trichaceae. 
Algae. 
Murray’s Introduction to the Study of Seaweeds.j; — After an 
Introduction, treating of the distribution of seaweeds and the best mode 
of collecting and preserving them, Mr. G. Murray classifies the existing 
forms into five sub-classes, viz. the Phaeophyceae, Chlorophyceae, Dia- 
tomaceae, Bhodophyceae, and Cyanophyceae. The Fucaceae are made a 
family of the Phaeophyceae. Under the Chlorophyceae are included the 
Peridinieae, Coccospheres, and Bhabdospheres. The Bhodophyceae are 
* Proc. Koy. Soc., lviii. (1895) pp. 195-204 ; Ann. Bot., ix. (1895) pp. 525-35. 
f Flora, lxxx. (1895) pp. 459-86 (1 pi. and 13 figs.). 
i London, 8vo, 1895, xyl and 271 pp., 8 pis. and 88 figs. 
