BERRY: A NEW MATONIDIUM FROM COLORADO 289 
ant remains (PLATE 12, FIG. 2) areabout 8 mm. inwidth. Several 
sterile fragments which I have referred to this species on the 
basis of general form and association are somewhat larger(PLATE 12, 
FIG. 7) being 15 mm. wide. These show a narrower rachis with 
slightly less obtuse pinnules which are greatly crowded, and may 
represent fragments of a contemporaneous species of Cladophlebis. 
Fertile fragments of pinnae present a very different appearance 
when the opposite faces are viewed. From below the rachis 
appears very stout and the laminae of the pinnules is entirely 
hidden by the large sori except for a broad band in the position of 
the midvein. Viewed from above the rachis is much narrower, the 
pinnules evidently having been inserted near the upper margin 
of the rachis as shown in the section (PLATE 13, FIG. 4). 
The pinnules are short and broad, more or less falcate, obtusely 
rounded at their tips. All have revolute margins and they are 
opposite or sub-opposite in position. Their substance is thick and 
the venation cannot be made out in any of the preserved material. 
Distad along the rachis the pinnules gradually become shorter 
and somewhat broader relatively (PLATE 12, FIG. 6), eventually 
becoming very small and coalescent basally (PLATE 12, FIG. 3, 4), 
their revolute margins giving them a pointed appearance. Proxi- 
mad along the rachis the pinnules gradate through short and 
broad forms to short wide scallops as shown in PLATE 12, FIG. 5. 
The sori are in two rows separated by a broad space in the 
region of the midrib. They diminish in size toward the pinnule 
tips and are prevailingly circular except where mutual crowding 
causes the lateral margins to be somewhat flattened. They stand 
out from the surface of the pinnules as prominent umbos and a 
‘pronounced umbilicus on the indusium marks the position of the 
central soral axis. The indusia are peltate and are intact in all 
of the Colorado material so that the number of sporangia can not 
be made out. In Matonidium Althausii the sori are said to have 
been more numerous than in the modern Matonia pectinata, 
sections of a sorus of the latter species being introduced for com- 
parison on PLATE 13, FIGS. 1, 2. _In the bulk of the material each 
pinnule shows three or four upper and four or five lower sori (PLATE 
13, FIG. 3). These were the only forms in the collection which 
Professor Cockerell had labelled Matonidium Althausu. In the 
