70 Rhodora [APRIL 
showing a strong tendency to be bidentate or bilobed, and by its 
deeply bifid ovate underleaves. Most of these peculiarities will also 
separate it from C. fissa Raddi, the type of the genus, which is perhaps 
to be expected in southern New England. This species also has more 
or less bidentate leaves and deeply bifid underleaves, but the teeth 
of the leaves are usually sharp, and the underleaves are considerably 
broader than long. 
C. tenuis is of about the same size as C. sphagnicola and grows in 
similar localities. Its more widely spreading leaves and its larger 
leaf-cells, destitute of trigones, will at once serve to separate it. From 
C. suecica it may be distinguished by its loose habit and larger, thin 
walled cells. Although C. tenuis does not agree with any of the recent 
European segregations from C. Trichomanis, its detection in Europe 
would not be surprising. 
10. Catypogria 'TuicuowaNis (L.) Corda. The range of the 
present species extends across northern Asia, Europe and North 
America. 'Phroughout this wide territory it is abundant nearly 
everywhere and has already been reported from each of the New Eng- 
land states. In its most typical condition it is found on soil rich in 
humus, either on shaded banks or in the woods. Under these circum- 
stances the plants are more robust than in any of the preceding species, 
the leaves often attaining a length of 2 mm. and a width of 1.5 mm. 
Such leaves are imbricated and ovate, spreading from the stem at 
an angle of about 60 degrees; they are either rounded or very obtuse 
at the apex and at the base are straight and slightly or not at all decur- 
rent. ‘The underleaves are orbicular and close together but rarely 
imbricated; they attain a maximum length of about 1 mm. and are 
bifid one fourth or less with rounded divisions and a shallow, usually 
rounded, sinus. At the base they are more or less decurrent and are 
attached by an arched line; supplementary lobes on the sides are 
wanting or very infrequent. The leaf-cells average about 50 X 40 gi 
but vary considerably both in form and in size. Their walls are thin 
throughout or very slightly thickened and do not show distinct tri- 
gones. 
When the species grows on sandy soil or in very wet places some 
of the characters which have just been described show themselves to 
be unstable. The leaves, for example, tend to become long-decurrent 
and sometimes show indications of apical teeth, while the underleaves 
tend to become smaller, more deeply bifid and with sharper divisions. 
