THE ANATOMY AND AFFINITY OF STROM ATOPTERIS MONILIFORMIS, METT. 137 
compared Stromatopteris with Platyzoma as extremely xerophilous and with the 
aspect of extreme reduction. 
The foregoing survey will suffice to show how little has been added by later 
authorities to Mettenius’s original statement. The kinship of Stromatopteris and 
Gleichenia has indeed remained unchallenged, and the demonstration of a protostelic 
axis in the former is valuable ; but apart from this, nothing has been advanced to 
finally establish its affinity, or further define its position within the group. The 
anatomical states of a plant undoubtedly provide valuable systematic data, but in 
themselves they are seldom determinative, for conservatism in these may be linked 
with advance in other characters, and the converse is equally true. It is, in fact, on 
the summation of characters that a reasonable conclusion regarding any organism 
may be founded, and it cannot be said that the summation for Stromatopteris has 
been completed. It is the object of the present memoir to provide details regarding 
the external form, the dermal appendages, the anatomy of stem and leaf, soral con- 
structions, sporangial form, and spore-output of Stromatopteris, and thus to render 
possible a clearer view of its> near affinities. 
Description of Materials. 
The materials available for study were two incomplete herbarium specimens and 
a fertile leaf, courteously supplied by Dr Maiden, F.R.S., of the Sydney Herbarium ; 
and although it has been impossible to obtain from these the valuable information 
which a study of sporangial development would have provided, it is believed that 
the facts of mature anatomy are in themselves sufficient justification for the present 
statement, and will go far towards establishing the nearer affinity of Stromatopteris. 
For purposes of description and comparison it is convenient to deal with the plants 
separately, and withhold the general consideration of form until the fuller facts of 
anatomy have been discussed. 
In the first specimen (figs. 20, 58) the slender, erect, and cylindrical axis is 
incomplete below. Towards its base it is branched, but the right-hand limb of the 
branching has been broken off. A slight displacement from the vertical occurs in 
the left branch immediately above the point of forking, but the erect position is 
resumed in it, and maintained for about -g- inch. Above this a second forking occurs, 
resulting in the formation of two diverging limbs. Close to its base the right limb 
is divided into two unequal branches, the left-hand member of which is short, conical, 
and complete. It is almost horizontal in position, and is little more than -g- inch in 
length. It appears, indeed, to be merely a short lateral appendage of- the right-hand 
member. The latter continues vertically upwards for over 10 inches, and, without 
further branching, ends abruptly in a fractured surface. There are two marked 
differences of appearance between this latter branch and the lower portions of the 
plant so far considered. The latter are rugged and cylindrical ; the former — except at 
