W. M. Fontaine — Mesozoic Plants from California. 275 



plants as Tceniopteris Orovillensis^ Podozaraites lanceolatus^ 

 and Ctenophyllum densifolium^ were very common, Cienis 

 auriculata, C. grandifolia^ Ctenophylliim grandifolium^ var. 

 Storrsii^ were less abundant, but still common. The rest 

 occur more rarely, and some, such as Adtantites Orovillensis^ are 

 found only in a single specimen. The plants, considered in 

 their identical and most nearly related forms, range in time 

 from the Rhetic, or uppermost Trias, to the Potomac. No 

 plant is identical with any belonging to the Potomac, and only 

 a single one, Ctenophyltum Wardii, has relationship with a 

 Potomac form, viz. ; Ctenophyllum latifolium, Font. There 

 can then be no doubt that the age is not Potomac. The fol- 

 lowing plants do not show a sufficiently near relationship with 

 known species to indicate any particular age : Adiantites Oro- 

 villensis, Macrotceniopteris nervosa, Ctenis grandifolia, C. 

 auriculata, C. Orovillensis. Compared with uppermost Trias 

 and Phetic plants, we find, in the Oroville flora, one whose 

 identity is doubtful, viz. : Sagenopteris rhoifolia, and four 

 which show pretty close relationship. They are as follows : 

 Ctenophyllum angustifoliicm, which is much like C. Brau- 

 nianum / C. densifolium, C. grandifolium, var. Storrsii / 

 which are near, the latter especially, (J. grandifolium of the 

 older Mesozoic of Virginia; Tceniopteris Orvillensis j which 

 is much like T. tenuinervis, of the Infra-Lias (Phetic) of 

 France. As most of these are common plants in the Oroville 

 flora, there is in it a pretty strong element indicating, by relation- 

 ship not identity, an age near the beginning of the Lias. If we 

 make a distinction between the members of the Jurassic as 

 Lias and Oolite, and if we admit, as we probably should, the 

 correctness of FeistmanteFs contention, that the age of the 

 Pajmahal Series is Liassic, we flnd a strong element in the 

 Oroville flora pointing to both a Liassic and Oolitic age for it. 



Three of the plants are doubtfully identified with Liassic 

 ones, viz. : Pecopteris gleichenoides f, Cladophlebis Indica f, 

 and Pterophyllum Pajmahale7ise f, and three show affinities 

 with forms of that age. These are Cladophlebis densifolia^ 

 Angiopteridium Calif ornicum, Macrotceniopteris Calif ornica; 

 six of the plants occur in the lower Oolite, and two are identi- 

 fied doubtfully with lower Oolite species. The six Oolite 

 forms are Cladophlebis spectabilis C. argutuhcs, C. Whit- 

 biensis tenuis, var. a, Podozamites lanceolatus, P. lanceo- 

 latus latifolius, Pagiophyllum Williamsoni. The two doubt- 

 ful forms are : Thyrsopteris Maakiana and Pimcs Nordens- 

 hioldi. 



From this it will be seen that the evidence that the age is 

 Jurassic, is stronger than that for any other, and as the Oolitic 

 plants predominate, we may assume with considerable proba- 

 bility, that it is rather late Jurassic, being about that of the 

 lower Oolite. 



University of Virginia, August 11th, 1897 



