68 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Muscinese. 
Peristome. * — M. Philibert continues to describe the differences 
between the Nematodonteae and the Artbrodonteae ; and points out 
certain transitions between these two groups. The genus Encalypfa can 
be divided into three principal sections, the peristome of which belongs 
to three different types: — (1) E. ^rocera and streptocarpa show a well- 
characterized diplolepideous type. (2) E. longicolla, hrevicolla, and 
apophysata represent the nematodonteous type, passing by degrees to 
the arthrodonteous. (3) E. ciliata, rliabdocarpa^ vulgaris, and commutata 
form a third group, which includes most of the non-European species, 
where the peristome presents first the aplolepideous type, and then dis- 
appears completely. 
The author concludes by describing the remarkable structure of the 
peristome to be found in the genus Splachnum, where we have an outer 
network, and beneath this a second network, and finally a third. This 
singular structure of Splachnum can easily be interpreted, and it will be 
found to belong to the general type of the diplolepideous peristome. 
Sphagnacese and the Theory of Descent.t — Er. E611 recurs to the 
consideration of the vast number of intermediate stages which bridge 
over the space between any two extreme forms in the genus Sphagnum, 
and proposes the construction of a genealogical tree which shall elucidate 
the relationships of the various forms to oneanother. He repeats his 
suggestion of the appointment of a “ sphagnological ” committee for the 
purpose of determining the limits of species or of forms, and questions 
of priority in nomenclature. 
“ Species” of Sphagnaceae.}: — Herr E. Eussow, from the examination 
of an enormous amount of detail of the bog-mosses, concludes that the 
variety of form is greater, and the limitation of species more difiicult, 
than in the typical mosses or in other groups of plants. The author 
defines the term “ species ” in relation to Sphagnacem as a group of 
forms consisting of members united to one another in all directions, and 
sharply separated from another group of the same nature, it may be by 
only a single character. 
Alg^ae. 
Thallus of Delesseria.§ — Mr. M. C. Potter describes the structure 
of the thallus of Delesseria, especially D. sanguinea. It is differen- 
tiated into a well-marked foliar expansion and a cylindrical portion — 
the “leaf” and the “stalk.” The “leaf” is, with the exception of the 
“ veins,” only one cell in thickness ; and the protoplasm is everywhere 
continuous from cell to cell through pits in the cell-walls. The 
“ veins ” are arranged like those of the leaf of a Dicotyledon, and are 
several cells in thickness, the cells being elongated instead of polygonal, 
like those of the rest of the leaf ; their protoplasm is continuous, 
» Rev. Bryob, xvi. (1889) pp. 67-77. Cf. this Journal, 1889, p. 673. 
t Bot. Ceutralbb, xxxix. (1889) pp. 305-11, 337-44. Cf. this Journal, 1888, p. 775. 
X SB. Dorpat. Naturf.-GeselL, 1888, pp. 413-26. See Bot. Centralbl., xxxix. 
(1889) p. 347. 
§ Journ. Marino Biol. Ass., i. (1889) pp. 171-2 (2 pis.). 
