io Oliver and Salisbury, — On the Structure and 
pyle, and passing into the stalk below more abruptly. Thus, disregarding 
the peduncle, the seed, as seen in longitudinal section, was approximately 
boat-shaped — the apex representing the prow and the base the stern 
(R. hi, PI. I, Fig. 1). 
There is only a single transverse section, somewhat distorted in form, 
owing to its obliquity both to the axis of the seed and to the two ridges 
first cut ; but if reliance can be placed on this solitary section, the seed was 
flattened, to a very slight extent, in a plane passing symmetrically between 
the angles, two of which were thus rendered more obtuse (Text-fig. 3, c). 
At these angles the sclerotesta was thickest, whilst it was thinnest at the 
other four (R. 119, 2, PI. I, Fig. 5, ma., mil). At the apex the angling 
of the middle region passes into definite ridges which end around the 
micropyle in six not very prominent lobes (Text-fig. 3, a). 
In the basipetal direction the angles develop as prominent ridges 
(R. no, PI. I, Fig. 4) and must have extended downwards, giving a winged 
B 1 
Text-fig. 4. Cells of palisade layer of the testa cut obliquely, showing the forward slope at the 
apex and the backward slope at the base (left of fig.). R. 122. a , cells of testa in surface view. 
character to the seed stalk. (In the instance referred to they are exag- 
gerated by reason of the obliquity of the plane of section.) Although six 
ridges appear to have been the general rule, variations, which are so 
marked a feature of the ribbing in Physostoma , no doubt occurred, .if only 
in the direction of increase. The instance is shown in R. no, PI. I, 
Fig. 10, r 7 , where a seventh rib is seen on the left. In one other case, 
although the number of ribs remains constant, two of them were abnor- 
mally close together. 
The internal form of the testa was, in the main body of the seed, 
similar to that of the exterior. The absence of transverse sections at 
the base leaves the lower limits of the interior doubtful ; at the apex 
the cavity was dome-shaped, passing into the funnel-like lower end of 
the micropyle. The dome-shaped apex of the cavity and the acute apex 
of the exterior thus rendered the testa around the micropyle of con- 
siderable thickness (0-57 mm.) as compared with that of the general 
body of the seed (0-13 mm.). 
In detail, the testa, like that of Lagenostoma Lomaxii , consisted of 
two kinds of elements, viz. an outer palisade layer and an inner hypo- 
derm. Seen in transverse section the palisade layer presents the form 
of a continuous investment of radially elongated elements about 70 p in 
