—75- 
how impossible it becomes to devise any key that will separate them 
even by a single constant character. 
In this confusion of groups one stands out distinct in general ap- 
pearance and certain anatomical characters, viz., the Rigida. This I 
have distinguished as an independent section, using the appropriate 
sectional name given it by Carl Muller in 1887,^ Malaco sphagnum. 
The other groups differ so very little from each other in comparison 
with their common difference from this group that I have not hesi- 
tated to include them in a single section, using for it the sectional 
name proposed by Carl Muller for the Cuspidata, viz. Acisphagnum. 
Of the disposition of its numerous species I shall speak later on. 
The most characteristic feature of Malacosphagnum is its cortical 
branch-cells, which are homogeneous, all of the flask or retort type, 
though the neck may be very short and inconspicuous, while in Ad- 
sphagnum they are of two sorts, the retort-cells larger and occurring 
singly or in twos, one above the other, in the axils of the leaves. 
This difference is noted by Carl Muller ( Berol. ),^ but has not previ- 
ously been made a basis for classification. It forms a clearly recog- 
nizable diagnostic character separating two natural groups. 
Of the two sections, Malacosphagnum seems both in general appear- 
ance and in the form and border of its leaves to be the more nearly 
related to Inophloea, without in any way bridging over the gap or in- 
validating the latter’s claim to recognition as a subgenus. My con- 
ception of the natural relationship of these groups could be repre- 
sented thus : 
Sphagnum 
Inophloea Litophloea 
Malacosphagnum Acisphagnum 
Ithaca, New York. 
MUSCI ACROCARPI BOREALI-AMERICANI 
Nos. 276-300 
Prof. Holzinger’s exsiccati continue the high standard set in the 
earlier fascicles. This fascicle contains six species from the moun- 
tains of Colorado, including Aulacomnium papillosum (C. M.j Jaeg. and 
Grimmia incurvata Schwaegr. Coll. H. S. Jewett. 
Eight from Montana, Coll. R. S. Williams, including Roellia lucida 
(E. G. Britton) Kindb., Bryum capitellatum C. M. & Kindb., Grimmia 
4. Flora 70 ; 404 C, M. had used some of his sectional names as substitutes 
for the current group-names for a number of years prior to this publication. 
5. Engler und Prantl, 1. c. , p. 181, f. 1894. 
