CRETACEOUS CONIFERALES 67 
the anther sacs do not open by a stómium аз is the case in Podocarpus 
and Dacrydium and, moreover, their microspores are not quite of the 
type found in the genera just mentioned. 
Figure 3, Pl. 24, shows a view of a transverse section of one of these 
aments, X 30. Inthe center is the axis containing a number of small 
fibrovascular bundles, arranged in a circle. These bundles are of no 
diagnostic value, although well preserved, for they are entirely com- 
posed of spiral ringed and reticulate elements, as regards the xylem, 
and consequently do not show any pitted tracheids, which could be 
used to establish the systematic position of the remains. From the 
surface of the axis are, derived a number of microsporophylls, each 
of which bears a pair of anther sacs. The pollen in the anther sacs, 
as has been pointed out, is winged, with two air chambers. Figure 
2, Pl. 24, shows a longitudinal view of one of these small cones, 
X 30, as seen in tangential section. The fact that the anther sacs 
are in pairs may more readily be made out in this plane of section. 
In the right of the section may be distinguished the end of one of 
the microsporophylls. It is obviously tipped with a distinct process. 
Figure 4, Pl. 24, shows the process, X 100. It is largely occupied 
by a mass of transfusion tissue which forms a cordon about the 
bundle entering from the sporangiferous part of the lamina of the 
sporophyll. Figure 5, Pl. 24, shows a transverse view of the upward 
process of another microsporophyll X тоо. The center of the 
process is occupied by the small cells which constitute the fibro- 
vascular bundle proper. The bundle is in turn surrounded by a 
cordon of larger cells with bordered pits—the transfusion elements. 
Figure 6, Pl. 24, shows an image of some of the microspores, X 500. 
One of these below the center of the photograph shows a wing with 
particular clearness on the left, the corresponding right wing is only 
partially represented. In one of the microspores above and on the 
right is seen a transverse section through the two wings. 
In living Coniferales air chambers occur in only two tribes, the 
Abietineae and Podocarpineae. In the Abietineae they are confined 
to the genera, Pinus, Picea, Pseudotsuga, Cedrus, Abies and Pseu- 
dolarix and are absent in Tsuga and Larix. In the case of one 
species of Tsuga, however, according to Lemon they аге sometimes: 
present. In the Podocarpineae all the genera with the possible 
exception of Saxegothaea have winged microspores. There are no. 
other examples among the living Coniferales of winged microspores.. 
