ON SOME NEW SPECIES OF FOSSIL PLANTS FROM THE 



LIGNITIC FORMATIONS. 



INTRODUOTIO]!^. 



A considerable number of specimeus have been lately delivered to me 

 for examination by Prof. P. V. Hayden, who obtained them from clay 

 and sandstone strata at or near Point of Eocks, a station of the Union 

 Pacific Kailroad between Black Butte and Salt Well stations, Wyoming 

 Territory. From Professor Meek's reports, and from my own, it will be 

 seen that from Black Bntte to Point of Rocks, in following the railroad, 

 the eastward dip of the measures brings successively in view a series of 

 heavy sandstones iuterstratifled with beds of clay and lignite, whose 

 whole thickness, according to Messrs. Meek and Bannister, is estimated 

 at 4,000 feet.* My own estimation gives only half this thick- 

 ness. But as I did not take any measurements, the purpose of 

 my explorations in that part of the country being essentially the 

 research and study of vegetable remains, I readily admit the con- 

 clusions of those distinguished geologists who had time to attend to 

 details of stratigraphy. At Point of Eocks, therefore, in following the 

 base of the sandstone ridge from Black Butte station, we have passed 

 such a heavy series of formations that, if any part of this so-called Bit- 

 ter Creek series is Cretaceous, even Upper Cretaceous, we should expect 

 to find in the fossil plants collected around this locality a number of 

 species of Cretaceous types, or at least a great modification in the char- 

 acters of the plants. The question will be more clearly examined and 

 understood after the exposition of the specific characters of the vegetable 

 remains which are described here below, and of the evidence of their 

 relations. All these species from Point of Eocks have been already 

 carefully figured from a large number of specimens, in five supplemen- 

 tary plates for the monography of the liguitic flora. 



DESCEIPTIO}^ OP SPECIES PEOM POIKT OP EOCKS. 



1. Lemna? bull ATA, s}). nov. 



Prondsl large, varying in diameter from one to three and a half cen- 

 timeters, broadly obovate, or nearly round in outline, bordered from 

 above the base and all around by a wavy margin four to five millimeters 

 broad, generally gradually narrowed into a short pedicel about three 

 millimeters thick, and terminating into a bundle of radicles. 



This vegetable form represents a floatiog and somewhat bladdery 

 plant; for, according to the plan of compression and of flattening, it is 

 either quite round, with the base of the pedicel marked by a round knob 

 in the center, or gradually narrowed to the pedicel where from the veins 

 are emerging in two or three thick bundles, dividing at the base of the 



* Dr. h\ V. Haydeu's toixth Aunual Keport, lor the year lc72, j). 533. 



