Campbell. — Studies on some Javanese Anthocerotaceae. /. 473 
The chromatophores in the assimilative cells of Targionia hypophylla are 
also few in number, and relatively large. The single chromatophore found 
in some of the species of Selaginella may be also mentioned in this con- 
nexion. These instances will serve to show that the chromatophores of 
the Anthocerotes are not so radically different from those of the other 
Archegoniates as has been generally assumed. 
Structure of the Thallus. 
The general form of the thallus in both M. Tjibode?isis and M. Sala- 
kensis resembles that of a typical Anthoceros , and in neither of these 
species could any trace of a mid-rib such as occurs in Dendroceros be seen. 
In M. giganteus, however, Goebel (loc. cit., p. 195) states that the thallus 
is costate, although not so distinctly so as in Dendroceros , which it 
evidently resembles in habit. This species showed two to four chroma- 
tophores, which, like those of M. Salakensis , were often joined together. 
No statement is made by Goebel as to the character of the apical cell, 
which in Dendroceros is quite different from that of Anthoceros . 
The thallus in both of the species under discussion is decidedly thicker 
than that of A. Stahlii, to judge from Stephani’s description. He states 
that in the latter the thallus is six cells thick in the middle and only three 
cells thick in the wings. The specimens of the typical form of M. 
Tjibodensis are from eight to ten cells thick in the middle, diminishing 
very gradually toward the margin to four or five. In no case was any 
part of the thallus seen with less than four cells. The larger form, growing 
on boulders, in some cases showed twelve cells in the central region. M. 
Salakensis is slightly thicker than the typical M. Tjibodensis — usually nine 
to ten cells in thickness. In both species, as in Anthoceros , the superficial 
cells are flattened, and the chromatophores larger than in the inner ones. 
The sub-epidermal layer is often quite well defined, the cells being inter- 
mediate in size between the shallow superficial ones and the four or five 
layers of large central ones. 
The apical growth is entirely like that of Anthoceros and the large 
initial cells show a regular succession of dorsally and ventrally arranged 
segments (Fig. 20). Each segment divides into outer and inner cells, and 
from the former in the fertile branches the sexual organs arise. In a few 
exceptional cases an approach to the condition found in Dendroceros was 
noted. In the latter genus the initial cells in vertical section appear semi- 
circular in outline, and segments are cut off from the inner face which 
extend the whole depth of the thallus, and are subsequently divided by the 
median wall into a dorsal and a ventral portion. Fig. 21 shows a section 
of the apex of the thallus of M. Tjibodensis , in which there is an approach 
to the condition found in Dendroceros . No intercellular spaces are present 
M m 
