Acrogynous Jungermanniales 291 
few involucral leaves in three rows, and finally the archegonial group 
surrounded by the perianth, these structures agreeing closely with 
the Cephalozia type, 
Protocephalozia ephemeroides is closely allied to Pteropsiella 
and placed with it in the Cephaloziaceag. Spruce, who discovered 
this curious little plant in Venezuela, growing on moist soil in shade 
and on mounds thrown up by mud-worms, says “ I had already 
found a minute Phascoid moss ( Ephemerum cequinoctiale) in similar 
sites; it is the only Phascum known to me that grows on the hot 
plains of the equator, and at first sight I took the Protocephalozia 
for a second species of the same genus, for I saw on the lumps of 
mould only a greenish confervoid film, with large perichaetia standing 
out of it here and there—very like the Ephemerum serratnm on our 
garden-pots in England. The prothallium of all Cephalozias is 
narrow and threadlike—very different from the suborbicular pro¬ 
thallium and propagula of Radula, Lejeunea, and many other 
Hepaticse: and it approaches the nearest of any among Hepaticae 
to the protonema of true mosses.” The vegetative organs consist 
simply of branching cell-rows, exactly resembling the filamentous 
protonema of Mosses and differentiated into an underground portion 
in which the cells have smooth thin walls and no chlorophyll, and 
an aerial portion which tends to grow erect, is profusely branched, 
contains chloroplasts, and has the cell-walls covered externally with 
papillate thickenings. At certain points on this protonema, the 
branches remain short, develop an apical cell of the usual three- 
sided type, and give rise to the leafy sexual shoots. The plant has 
a tufted habit, the usually solitary female shoot arising from the 
base and the male shoots higher up on the branching filaments. 
The classification of the Acrogynas here suggested is based upon 
that proposed by Spruce in his classical work on the Hepaticae of 
the Amazon and the Andes (78), with some slight alterations. 
A. Leaves typically divided into a large upper and a small 
lower lobe, the latter usually rolled up or saccate; underleaves 
usually present; perianth usually with wing-like ridges, contracted 
at the apex to a tubular beak, and ruptured irregularly by the 
exsertion of the short-stalked capsule; elaters few, with a single 
spiral fibre, all fixed by their upper ends to the inside of the capsule- 
wall and extending to the floor of the capsule-cavity ; archegonia 
from one to four (rarely more) in a group. 
1.—Lejeuneace^e. This is the largest family, including 
nearly 2,000 species of which the majority belong to 
