160 MESOZOIC FLORAS OF UNITED STATES. 



so that the plant matter of the pinnules is usually well preserved and 

 leaves a shining film on the stone. The rachis of the ultimate pinna is 

 winged by the decurrence of a pinnule, or lobe, placed in the angle between 

 the lower side of the. base of the ultimate rachis and the penultimate one. 

 The larger pinnules in PI. XXXIX, Fig. 9, the dentate ones, may be 

 regarded as normal for the frond. As stated above, they diminish in 

 ascending on the frond, and also toward the ends of the ultimate pinnas, 

 becoming entire and more united, until they pass into lobes and finalty 

 into teeth. The general character of the normal pinnules is maintained 

 until they are reduced to lobes and teeth, when the}^ become proportion- 

 ally l^roader at base, taking more or less of an ovate form. 



The normal pinnules are narrowly oblong and acute. They are 

 decurrent at base and united with the next lower ones, forming a narrow 

 wing on the ultimate rachis. On the upper side of the base thej^ are 

 slightly constricted, the constriction being more pronounced the deeper 

 the toothing. The larger and lower pinnules have minute teeth that 

 are acute and inclined strongl}^ toward the tips of the pinnules. They 

 often have a spiny look and can not be seen distinctly without the help 

 of a lens. The pinnules are generally straight, but may be slightly falcate. 

 They go off obliquely from the ultimate rachis and are inclined forward 

 toward its end. 



The midnerve of the pinnules is rather slender and continues to near 

 the end of the pinnules. The lateral nerves go off pinnately and ver}^ 

 obliquely. They are straight. In the toothed pinnules the lower ones 

 are once forked, the rest are single. In the entire pinnules and lobes 

 they are single. This plant has a good deal of resemblance to Aspidium 

 montanense Font." of the Kootanie strata of Great Falls, Mont. But 

 the Montana plant has the pinnules, lobes, and teeth more obtuse and 

 not so strongly inclined forward. PI. XL, Fig. 7 probabl}^ represents a 

 portion of a penultimate pinna from the upper part of the compound 

 pinna, where the ultimate pinnge carry pinnules reduced to lobes. It 

 shows the slender elongate form of these. Figs. 8 and 9 show enlarged 

 pinnules of this. 



The fossil Lesquereux determines as Pinus! Staratschini does not 

 seem to be Pinus. It looks like the rachis of Cladophlebis alata. 



'Description of some fossil plants from the Great Falls, coal field of Montana: Proc. U. S. Nat. Mus., Vol. 

 XV, p. 490, pi. Ixxxii; pi. Ixxxiii, figs. 1, la, 2, 3. 3a. 



