10 /■ ' i /■' tinct 1 Worth America, 



continent. It will b by the notes now given of the Ter- 



tiary flora of onr continent, that, at a later date, palms grew in 

 the same region where these Cretaceous plants are found; but 

 cinnamons and other tropical plants seem to be entirely ■want- 

 ing in the Tertiary flora of the central part of the continent, 

 while «'ii the wesl coast both palms and cinnamons lived during 

 the Tertiary period as far north as the British line. We have 

 therefore negative evidence from the facts, though it may be 

 reversed at an early day by further observations, that the cli- 

 mate of the interior of our continent during the Tertiary i 



- somewhat warmer than at the beginning of the Cretaceous 

 1 i ri< d, and that during both the same relative differences of 

 climate prevailed between the central and western portions that 

 exist at the present <l;n . 



DESCRIPTIONS OF SPECIES. 



Sphenoptcris cormgrata. (n. sp.) 



Form of frond unknown ; pinnules <<\ ate or cuneiform, narrow ed 

 .-it the base, obtuse, Lobed, often plicated longitudinally; nerves 

 distinct, dicbotomously branching from the 1>: ; 



The specimens of this fossil collected by Dr. Hayden are 

 fragmentary and imperfect, but quite sufficient to show it to 

 different from any described species. 



Formation and Locality. Lower Cretaceous strata, Black- 

 bird Hill. Nebraska. 1 1 >r. Eayden.) 



Araacaria spatnlata. (n.sp.) 



Tli<- onlj specimi n of this beautiful species contained in the col- 

 lections of Dr. Hayden, h a fragment of a branch nearlj hall' an 

 inch in diameter. On this the leaves arc thickly set, theif bases 

 htlj decurrcnt, being scarcely separated from each other. From 

 these bases, tin- leaves radiate in all directions, and are slightly 

 curved. Tbej arc half an inch in length, broadly Bpathulate, ob- 

 . and narrowed at the base. Along the medial line pass< s a « I i >■ 

 tin.-t carina, which vanishes towards the apex. 



I i all living or fosail specie-, this b< very clearly dis- 



hed by the form of the l< '' i pi of .1 rau- 



