On the Sorus of Dipteris. 241 
On the contrary, the method of arrangement and the character of 
the sporangia would seem to indicate that every available part of 
the flat receptacle had been utilised to provide for the production 
of spores. The paraphyses in section appear as short club-shaped 
structures with the end cell colourless and elongated. In Dipteris 
bifurcata the sporangium is large. It has a broad complete 
annulus, which appears curved or twisted owing to the unequal 
development of the tw r o faces of the sporangium, for the concave 
face is narrow, consisting of merely tw'o rolls of elongated cells, 
while the convex face is broad and bulged out, showing four or five 
rows of larger cells. The narrow face is the one exposed. There 
is a definite stomial region which is situated to the right or 
left side of the narrow face according to the position of the 
sporangium in the sorus. 
Throughout all the stages of the sorus in Dipteris bifurcata it 
is plain that the sporangia contained in it are all of the same age, 
i.e. they develop simultaneously. 
The distribution of the sori on part of the under surface of the 
large frond of Dipteris conjugata is shown in Fig. 13. In accordance 
with the description already given by other writers, it will be seen 
that the sori “vary in size and shape,” and are “often confluent.” 
Compared with the mature sorus of Dipteris bifurcata, the sorus of 
Dipteris conjugata is small, and may contain from twelve to seventeen 
sporangia, loosely arranged and separated from one another by the 
paraphyses, which have the terminal glandular cell much bulged and 
of a rich brown colour. The sporangium also is small, but shows 
the main characters of the sporangium of the other species. As 
has been noted, the annulus is oblique. The ripe sporangia in the 
specimens examined gave clear evidence of the presence of a definite 
stomium. The material of Dipteris conjugata from Mount Ophir 
did not afford any specimens showing the youngest stages of the 
sorus. The earliest stage observed is shown in Fig. 11, ( 5 ) which 
illustrates the fact, already stated by Seward and Dale, that the 
sporangia in this species do not arise simultaneously. This is still 
more clearly shown in ( 6 ) representing a more mature state. 
The genus Dipteris thus includes one species, Dipteris bifurcata, 
which shows simultaneous development of the sporangia in each 
sorus and conforms, therefore, to the “Simplices” in Professor 
Bower’s classification, and another species, Dipteris conjugata, 
having sporangia of various ages present in the same sorus and 
it conforms, therefore, to the “ Mixtae.” The external characters 
