PLATE XLVIII. 



Bbittsia problematica D. W. 



(Page 98.) 



Fig. 1. Froud showing flesliy expansions of the central axis (rachis) and pinnje. The thick, appar- 

 ently veinless, thalloid lobes of the latter are seen on the left. In the lower left fragments 

 of the pinnules overlying the fleshy bordered rachises are seen. U. S. Nat. Mus., 5723. 

 la. Enlarged detail of the lower left of the same specimen, showing jiortion of main axis and four 

 pinn;e with their fleshy expansions or thalloid lobes. The vascular system is also indi- 

 cated. Toward the margin portions of several of the pinnules expanding in a plane 

 above the rachis are seen, with their dentate margins. The individuality of the pinnules 

 is not clear in the figure. X2. 



2. Photograph of portion of frond from which the rachial plane has been broken away, leaving 



the imbricated pinnules in the matrix. (See 2a.) U. S. Nat. Mus., 5811. 

 2a. Enlarged photograph of the same. The remains of the double (parallel) rows of pinnules of 



three pinnn; are seen, especially the two rows of one pinna on the right. x2. 

 2b. Detail of the same showing the broken remains of the two imbricated rows of pinnules or 



scales of the pinna on the right of Fig. 2a. The basal portions of the pinnules which 



narrow to the sinuses between the lobes of the rachis are broken away. The pinnules 



are not so striated as the drawings la and 26 indicate. x2. 

 2c. Detail showing pinnules in left of Fig. 2. The thick nerves and several of the teeth of the 



pinnules are seen, while the trend of the nerves toward the sinuses, and the vascular bands 



of the rachis are indicated. The impressions on thi underlying fleshy rachis indicate a 



considerable length for the basal portions of the pinnules. x2. 



3. Small frond showing axis, pinnaj which are somewhat radiately disposed, and fleshy lobes of 



the rachis, the borders of the lobes being overlain in places by fragments of the over- 

 lying compressed pinnules. U. S. Nat. Mus., 5722. 



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