— 535 — 
Ils characters are essentially those of thé border rib shown in VI. x 
lig. 1, hough smaller, the tubercles on the midril, Fig. 3, being su 
short and small as to impart a granulose appearance. The presence of 
tubercles in normal size and arrangement on the lamina overlying the 
flattened axis, seen at the base of this figure, indicates a continuity of 
the sporangiate integument, across the midrib, in a way hardly com- 
patible with a fillcoid median nerve. (1). 
The specimen, Fig. 3, is slightly concave wilh tubercles in relief, 
while the slightly convex counterpart, ig. 4, shows the tubercles as 
indented impressions in the matrix. Iam disposed tu regard the latter 
as the impression of the ventral surface of theorgan or member. Irom 
the bilateral symmetry of this specimen we may conclude that it is 
probably a medial fragment. 
Yhe original of Fig. 2, Pl. x, with its reverse, rig. 1, is perhaps 
the most interesline specimen in the collection. It represents the 
distal portion of a conspicuously asymmetrical member, at one side of 
which lies a thick, gently curved, spine-like marginal rib. In the 
counterpart, Fig. 4, the large tubercles and rib (2) are seen in strong 
impression, the former being clear and distinct, while the latter, 
nearly half round in the impression, is marked hy small crowded 
scale-tubercles comparable to those on the midrib of the original of 
Tig. 3. 
The tubercles in l‘iv. 2, are seen to be smaller near the lateral 
rib, and in the portion farther from the border they are also close. 
The border of the lamina, on the right, is marked by a narrow 
yone of short, crowded and somewhat imbricated scales or slightly 
projecting tubercles which give a denticulate profile, as is seen, photo- 
graphically enlarged, in Fig. 9, Plate xi. Similar though much smaller 
sealelike tubercles appear near the midrib, those nearest the latter 
being crowded and irregularly arranged. Farther out from the midrib, 
and before reaching the large labercles, the surface is sranulose 
like that shown four times enlarged in tle lower part of 12) eee 
Fig. 3. 
The positive, or relief, side of the specimen shown in Fig. | differs 
from the other chiefly in exhibiting a rather coarse, scaly, vesicular. 
is Compare the lower parts of ligures 3 and 4, Plate x. 
In speaking of the portions of the fram2 or skeleton of th: parts represented, 
the Sage yib avid midrid are used for convenience ralber than vs strictly and declines 
tely applicable. 
