Jungermannia N Sp. mac faddens Plants autoicous, branched, usually under 1 cm long minute. Leaves smallest below, enlarging upwards. smallest .35mm long, usually broader than long, broadly ovate, broadest at or below the middle. rad- ually coming to an obtuse apex. Concave. somewhat obliquely inserted below, but nearly transverse near the perianth, as are also the male bracts. Usually the leaves are subsecund above, much as in macVicar's plate of J atroviens. The leaves clasping stem, but not at all decurrent. Cells irregular above averaging 19u, varying from 13 to 28u. somewhat thick walled from contents clinging to walls. Minute trigones present. Basal cells in middle up to 18 by 30u, but not much larger than apical at margins. Surface verrucose. Perianths Rhizoids numerous on stems and innovations, colourless. Perianth usually lateral by innovations, from horizontal to suberect, ventricose above, 1.2mm long by .475mm wide. Broadest at or below middle, plicate from there above, gradually contracted to a narrow mouth .2mm wide, the mouth with numerous crenulations, short, to 2 cells long. Male bracts some distance below perianths, deeply concave, and transver- sely inserted. bracts below perianth up to 1.1mm long by 1.05mm wide, Perianth at base .3mm wide. Stem in section with outer row of cells, rather thick walled, 25 X 30µ, internal cells thin walled, abruptly differing from outer row. Averaging 15m wide. nearly hyaline Walls distinctly verrucose Type, Canyon Creek, Monte Vista Dam, Placer Co, California June 11th 1933 Coll F A MacFadden, in herb macfaddon. The continuous innovations give the plant a pleurocarpous character, and the perianths are sometimes curved. he irregular cells are very similar to those of J atroviens, to which the plant seems closest in relationship, but that plant is dioecous, with perianth is ovate to oblong-ovate, but is variable in shape, it however does not appear to have any tendency to approach the shortly-attenuate point of the above. The stem is section shows smaller cells, and while the outer are nearly as large as those of above, the inner are distinctly larger, averaging 20µm, and not marked off from the outer row. The perianth of J pusilla has some approach to that of above, but is more longly attenuate, and less markedly crenulate at mouth, also it is nearly always terminal in appearance, and shows no sign of being ventricose above, being rather fusiform. The leaves are larger, and while the pacical cells are not markedly larger, they are less irregular, more noticeably thin walled, and below they are distinctly larger, mostly some 50u long, or even longer. The marginal row is rather distinctly marked off. In stem section the J pusilla show but little tendency to differ, and though the outer are larger, 25 X 30, the inne are also larger than above, some 17u, gradually mixing with outer row, not distictly marked off. They are also distinctly firm walled. J Schiffneri has a different perianth, the male bracts are directly below the perianth, the leaves are distinctly different on the fertile branches from the broader than long leaves of the fertile stems. It has to be remembered however that other of the californian Jungermannia are variable, thus J Schiffneri from there has larger cells than usual, and a longer perianth, though variable perianth is also noticeable from material collected in B C and Alberta. Then J pusilla had not the longlyattenuated perianth usually found on European material. J Bolanderi is distinctly different, and the large decurrent leaves with "upper leaf cells 25-40u, and basal 45-96, will easily mark off from above. J Daniela is described as perianth obovoid, exserted, irregularly plicate towards the abruptly contracted, at first crenulate-denticulate mouth. The cell size given is larger also, 24-50u. J riparia has larger cells, more thin-walled, thin walled, smaller trigones cells, more regular, the perianth is quite different, though it is variable in size and shape; none being seen however with the "acute" mouth of the above