20 /. • /.' tin ' /"■ th America^ 



tomosing Dear the margins; net-work of tertiary veins somewhat 

 lax, but composed of nervules of such tenuity as to be rarely visible. 



This Is the planl of which an outline sketch was sent Prof. 



II. . : by Mr. Meek. In thai sketch the general form was alone 



. the details of nervation as well as the texture of the leaf 



not being deducible from it. Prof. Beer considered it a 



- 



Za !«, and as probably identical with Litmus primigenia 

 CTng., a common species in the Tertiary of Europe. Aside from 

 the ajpriori improbability of this plant found in the Lower- 

 I as rocks being identical with one which in the old 



world dates hack no further than the Miocene, there are char- 

 actersinthe fossil itself which seem to separate it from even 

 the genus of L. primigenia. The nervation has a differenl as- 

 pect from that of any of the Lauracea with which I am ac- 

 quainted, being both more lax and delicate, the secondary 

 nerves less accurately arched, and their summits more wavy ; 

 the patterns found by their anastomosis less regular and deter- 

 minate. In these respects, as well as in its comparatively thin 

 and delicate texture, it re.-eml>les much more the Willows than 

 Laurels. 



It seems hardly worth while to compare the plant before us 

 with any of the living Willows, for everything indicates that all 

 of the Chalk, both, vegetable and animal, long since 

 perished. Among the great number of fossil species found in 

 the Tertiary strata there are several which have a general re- 

 semblance to it. and from which it might be unwise to regard it 

 isti net if they were from the same Ion nation. Salix elongata 

 Web. (Tertiarflora der N"iederrheinischen Braunkohlenforma- 

 tion, Taf. .xix. fig. L0,) has nearly the same form, hut the second- 

 ary nerves are given i If at a larger angle, and are much more 

 arched. 



From its associate species in the Cretaceous strata it Beeme 



difficult to distinguish it. Solicited Hartigi Dunker(Paleou- 



aphica I. Band. 6, Lief. 81, Taf. xzxiv. fig. -J) isapparently 



much more Btrongly nerved. The general form was perhaps 



