158 Rhodora [SEPTEMBER 
pocket formed between the two lobes two or three antheridia are 
situated. The typical condition just described is not always realized, 
as Fig. 3 shows. The keel here is less rounded and the dorsal lobe is 
almost as long as the ventral, although still much narrower. The 
antheridia in bracts like these are sometimes borne singly. 
According to Miiller the stalk of the capsule consists normally of 
three concentric layers of cells, the outermost ‘numbering twenty in 
cross-section, the second twelve, and the innermost four. He admits, 
however, that there are deviations from these numbers, and the 
writer would refer the stalk to the “type général" of Douin, in which 
the number of cells present varies according to the robustness of the 
plants. The capsule shows the usual thickenings in the walls of the 
cells. Those on the outer surface average about 35 X 25 u and show 
rod-like thickenings in both longitudinal and transverse walls. On 
the inner surface the cells average about 13 u in width and usually 
measure 30-50 u in length. Each cell shows from four to ten half- 
rings, according to its length. The spores are 15-17 u in diameter and 
the bispiral elaters average 9 u in width. 
The various forms of N. hyalina in Europe have been carefully 
studied by Schiffner? who recognizes the three following varieties, 
in addition to the typical form of the species: var. heteromorpha 
(Gottsche) Schiffn., var. subaquatica Schiffn., and var. ovalifolia 
Schiffn. "These varieties have not yet been distinguished in American 
material, and the writer is not prepared to designate any of the Ameri- 
can forms by varietal names on account of the inconstancy of their 
characters. 
The synonyms of N. hyalina should evidently include N. biformis 
(Aust. Lindb., as indicated above. This species has long been a 
puzzle to students of the Hepaticae. It was based on male material 
collected in 1867 by Austin at the Delaware Water Gap, New Jersey, 
where it grew on steep, wet rocks. The original specimens were 
distributed in Austin's exsiccatae, and no additional stations for the 
species have been recorded. According to the original description 
the species is " remarkable for the closely entangled and matted stems 
and surculi, and for the leaves of two forms." The leaves of one 
form, borne on the stems, are said to be obliquely semicircular or 
broadly ovate, decurrent at the dorsal base, and entire or retuse at 
1 Bull. Soc. Bot. France 55: 274. 1908. 
? See Verhandl. Zool.-Bot. Ges. Wien 53: 418-421. 1904. 
