54 2 Dutt . — Pityostrobus macrocephalus, L. and H. 
Very often the prothallus contains a large central cavity, or sometimes 
there may be more than one. In the Cowderoy specimen of P. macro- 
cephalus these clear spaces are usually surrounded by an opaque black sub- 
stance, largely of carbonaceous nature, which has probably been derived 
by the decay of the prothallial tissue that has shrunk away from the centre 
of the cavity. 
The tissue of the gametophyte is remarkably homogeneous. With 
two exceptions not only are there no signs of an embryo, but there is not 
even evidence that, at the time of fossilization, differentiation of archegonia 
had taken place, even in the largest ovules. The two exceptional ovules 
were found in the cone of P. macrocephalus belonging to the Sedgwick 
Museum. In both the prothallus contains a body which undoubtedly repre- 
sents a nearly mature embryo (Figs, n, 12, PI. XV). The better preserved 
of these is of typical cylindrical shape, tapering at the ends and contracted 
below the insertion of the cotyledons, and is surrounded by a tapetum-like 
jacket of endosperm cells which can be exactly matched in recent pine-seeds. 
The cells of the hypocotyl, though not individually preserved, have every 
appearance of being arranged in regular meristematic rows, but the cotyle- 
donary apex is rather decomposed, so that neither the growing point nor the 
separate cotyledonary lobes can be distinguished. In this embryo the ex- 
tremity of the radicle is very close to the base of the nucellar column, and 
it is interesting to notice that at the apex of the latter there are a number 
of structures which can only be interpreted as germinated pollen-grains 
(Fig. 15, PI. XV). A suspensor could not be demonstrated ; but in view of 
the age of the embryo this is not surprising. 
In the other case the embryo exhibits at its apex a whorl of cotyle- 
donary lobes with indications of a growing-point at their base ; but other- 
wise it is less well preserved, and the middle region has become doubled up, 
presumably owing to the contraction of the apical region of the prothallus 
(Fig. 12, PI. XV). No trace of pollen-grains or of pollen-tubes could be 
found in this ovule. 
(v) The Male Gametophyte . 
At the apex of the nucellar column of the ovule shown in Fig. 7, 
PI. XV, there are two small rounded objects which most certainly represent 
two winged pollen-grains ; they can be seen more clearly under the higher 
magnification of Figs. 13, 14, PI. XV. The wing exhibits the charac- 
teristic reticulation seen in the pollen-grains of living pines, but this 
feature does not appear clearly in the photographs. These pollen-grains 
show no signs of germination. 
On the other hand, it has already been remarked that structures 
which must be considered as germinated pollen-grains occur at the apex 
of the nucellar column of one of the fertile seeds. These form a small 
