516 Descriptions of the Fossil Plants 



able, the beds containing it are Cretaceous, it will doubt- 

 less prove to be a new species. 



The only tangible characters exhibited in the specimens 

 yet obtained are in the nervation. 



The nerves are very fine, nearly sixty in each fold, — six 

 stronger ones on each side of the midrib, and between 

 each two of these three finer ones, of which the middle is 

 strongest. 



Taxodium occidentale Newb. 



Desc. Branchlets terete, leaves numerous, crowded, 

 generally opposite, sessile, or very short-petioled, one- 

 nerved, flat, rounded at both ends. 



This is the plant figured by Prof. Dana, (Geol. Explor. 

 Exped. Atlas, PI. 21, fig. 3,) and considered by Prof. 

 Heer — judging from that figure — as identical with T. 

 diibium, a species very common in the Tertiary of Europe. 

 Future investigations may confirm this identification, but 

 the specimens before us exhibit so well-marked and con- 

 stant differences from those of the European T. dvbium, 

 that we must conclude them distinct, at least till such 

 time as common characters may be discovered which shall 

 unite them. 



Judging from the leaves alone, for we have not yet met 

 with the fruit, if there is any propriety in separating T. 

 dubiuni from the living deciduous cypress T. distichnm, our 

 plant should be regarded as a new species, as it is more 

 unlike either than they are unlike each other. 



In T. dubiuni the leaves are fewer, more obliquely set 

 on the deciduous branchlets, are short-petioled, and acute 

 at both ends. Even in var. c. " foliis apice obtusiusculis," 

 (Heer, op. cit. p. 50, Taf. XVII. fig. 19,) there is no 

 very marked departure from the normal form, while in the 

 numerous specimens collected on the Pacific coast by Mr. 

 Gibbs and Prof. Dana — all of which are before me — the 

 leaves are mostly closely set, given off from the branchlet 



