190 
parts have lost it by formation of nemathecia or from other causes. The meeting 
point between the overlapping frond with another similar one or with the forth- 
growing old frond is usually easily found (fig. 112 B *). The places from which 
the new fronds are given off are frequently inverted conical, being upwardly en- 
larged and composed of filaments slightly diverging upwards. The number of these 
Fig. 112. 
Cruoriella codana. A, marginal part of frond seen from below. 195:1. 
the overlapping of the frond by a new lobe; at « the point of concretion of this lobe with another part of the frond; 
in C the basal layer of the new lobe is not normally developed. In C auxiliary-cell filaments and sporogenous fila- 
ments are visible 205:1. D, vertical section of frond with antheridial nemathecium. 350:1. 
B and C, vertical sections of frond showing 
points of departure is variable; sometimes they are very close, in other places they 
are more distant. The new-formed fronds coalesce laterally and form together a 
uniform plain surface. The cells of the basal layer of the overlapping fronds were 
frequently found connected with pits, a fact which supports the here proposed ex- 
planation of their development. As the new fronds were evidently not produced 
at the season when the specimens were collected, I have not been able to follow 
their development, but must content myself with examining the advanced stages. 
A further fact confirming my view is that nemathecia are frequently found on the 
surface of the covered crust (fig. 112 C). The under face of the frond is often 
