7l' Lat> /■ Extinct Floras of North Am, rica, 



gen ob. The aspect of the leaves of ( 'orn us is peculiar, and such 

 as is usually readily recognizable ar a glance. This fades is 

 given by the outline as well as the nervation. The outline is 

 usually more or loss accurately oval, the margin entire, the 

 base rounded or slightly wedge-shaped, the summit pointed 

 and laterally flexed. The nervation is very clearly defined, 

 the midrib strong at the base, tapering gradually till it reaches 

 the extreme point of the apex; the lateral nerves pinnate, 

 approximated below, more remote above; all simple, arched 

 upward, those near the summit being drawn in to join the 

 midrib. 



This latter characteristic is visible in all the species of Cor- 

 nus known, and is particularly noticeable in the common herba- 

 ceous species C. Canadensis. It is also very marked in C. 

 Florida, O. sericea, C. aliernifolia, etc. 



The tertiary nervation is generally delicate and sparse, the 

 tertiary branchlets running across obliquely, but with nearly a 

 straight course, between the adjacent lateral nerves. In all 

 these character-, as far as they are retained in the fossils before 

 US, we find an entire correspondence with the living genus 

 Corn us. and refer these leaves to that place in the botanical 

 series with as much confidence .as the foliary appendages alone 

 can give. 



Formation <nt<l Locality. Fine laminated sandstone, with 

 Platanus Haydenii and /'<>/>>////* X,hr<i.s<; ,,<■;*. Yellowstone 

 River. 1 1 >r. I [ayden.) 



Carya aiitiqiiorinii. (n. Bp.) 



Leaves pinnate, large, leaflets lanceolate, long-pointed, acute. 

 sessile, finely serrate, middle leaflet broadly lanceolate, widest above 

 the middle, narrowed to the base, which is somewhat unequal; 

 lateral leaflets narrow, lanceolate, onsymmetrical throughout, some* 



\\lia< falcate; nervation sharply defined, conspicuously parallel, 



medial nerve straighl in the terminal leaflets, more or less ourved in 



the lateral oik-; secondary nerves springing from the midrib af b 



angle, numerous, sub-parallel, all arohed upward, their ex* 



