FLORA OF THE FRUITLAND AND KIRTLAND FORMATIONS. 



335 



Wind River Basin by Woodruflf in 1909, and 

 in the Jiulitli River formation along Milk River, 

 Mont., by Pepperberg in the same year. The 

 questionable reference to tliis species of the 

 specimens collected in 190S near jilesua Moun- 

 tain, N. Mex., by Gardner is now rendered 

 more probably correct by the evidence of the 

 present specmien. 



The genus Pistia has had a very interesting 

 geologic history. It is represented in the liv. 

 uig flora by a smgle variable and widely dis- 

 tributed species {Pistia stratioles Lmne). It is 

 mainly tropical, ranging in tliis country from 

 Florida to Texas and thence tlnough the West 

 Indies, Mexico, and Central America to Para- 

 guay and Argentina. In Africa it ranges from 

 Natal to Senegambia and Nubia, and thence to 

 Madagascar and the Mascarene Islands. In 

 Asia it is found throughout the East Indies 

 and thence to the Pliilippines. 



Of the four or five fossil species recognized, 

 thi-ee are found m North America. The oldest 

 of these is Pistia nordenslioldi (Heer) Berry,' 

 which occurs in the Magothy fonnation of 

 Maryland and very abimdantly in the Black 

 Creek formation (Turonian) of North CaroHna. 

 It was first described by Heer = under the name 

 Chondrophyllum nordenskioldi, from specimens 

 found in the Atane beds of Greenland. 



The next species in point of age is Pistia cor- 

 rugata Lesquereux, wliich has already been dis- 

 cussed. 



The youngest American fossil form is Pistia 

 daibornensis, from the Claiborne group (nud- 

 dle Eocene) of Georgia, recently described by 

 Berry.' Tliis differs markedly from the other 

 forms by its obovate shape and strongly rotuse 

 apex. 



The only accepted European fossil species is 

 Pistia mazeli Saporta and Marion/ which occm-s 

 in the lignites of Fm-vean (Provence), France, 

 and is of approximately the same age as Pistia 

 corrugata. Pistia mazeli appears to be most 

 closely related to the living form; in fact in the 

 figures of the two species given side l^y side by 

 Saporta and Marion it is ahnost uupossible to 



1 Berry, E. W., Torrey Bot. Cluh Bull., vol. 37, p. 189, pi. 21, flgs. 1-1.5, 

 1910. 



2 Heer, Oswald, Flora fossilis arctica, vol. 3, p. 114, pi. 30, fig. 4b; pi. 

 32, flgs. 11,12, 1S74. 



» Berry, E. W., U. S. Geol. Survey Prof. Paper S4, p. 137, pi. 26, flgs. 

 1-2, 1914. 



* Saporta Gaston, and Marion, A. F., L't^vohitiou du r&'HJe v<5g6tale, 

 Phandrogames, vol. 2, p. 37, flgs. 114c, 114d, 1S.S5. 



note marks of distinction. In some ways it 

 appears that the Claiborne species {Pistia 

 daibornensis) is most closely related to Pistia 

 mazdi, except that it is more retuse at the 

 apex. However, its full character has not yet 

 been made out, as it still depends on a single 

 example in whicli little of the nervation has 

 been retained. 



The other two species {Pistia corrugata and 

 Pistia nordenshioldi) are themselves closely 

 related and are also close to the Uving species, 

 the main difference being their larger size and 

 more anastomosing nerves. 



The significant point brought out by this 

 cUscussion is the fact that tliis peculiar plant, 

 now so widely distributed over both hemi- 

 spheres, was estabhshed in essentially its present 

 form in late Cretaceous time, and even then 

 occun-ed in both hemispheres. It is rather 

 remarkable that so little has been ascertained 

 regarchng its Cenozoic history, in view of the 

 great niunber of locahties that have been 

 investigated, yet the evidence that it must have 

 persisted with very little change is brought out 

 by the above exposition. 



Occurrence: Kirtland shale, 1\ miles north- 

 east of Pina Veta China, San Juan County, 

 N. Mex. Lot 96 (6065). 



Family PALMACEiE. 

 Sabal montana? Knowlton. 



Plate LXXXV, figure 2. 



Sabal montana Knowlton, IT. S. Geol. Survey Prof. Paper 



101, p. — , pi. 32, fig. 3 (in jwess). 

 Sabalit.fs yrai/anus (Lesquereux) Lesquereux, IT. S. Geol. 



Survey Terr. Rept., vol. 7, p. 112, pi. 12, fig. 1 [not 



pi. 12, fig. 2], 1878. 



Most fossil palms an* very difficult to identify 

 and as a consequence are more or less unsatis- 

 factory as stratigraphic criteria. The leaves 

 are commonly of very large size and it is dif- 

 ficult to prociu'c specimens that are anywhere 

 near perfect, essential characters being in many 

 specimens lacking or obscure. A specimen 

 perhaps no larg(*r than one's hand from a leaf 

 that was possibly 5 or 6 hvt in diameter can not 

 fail to convey a very inadequate idea of its 

 character, particularly the range in mdividual 

 variation, and it is not at all improbable that 

 too many species have been established. 



The specimen under considei-ation is a case in 

 pomi. It isi a fragment, only about 10 centi- 



