32 



smooth surface and without articulations. These characters are 

 common to a large number of marine Algae of the present epoch, 

 especially to species of Chondrus. But the relation of fossil to 

 living plants is based on a mere superficial likeness ; for the 

 living Algae are now grouped and classified according to the 

 characters of their organs of reproduction, rather than by the 

 appearance, size and form of their fronds and branches, the 

 only parts which remain observable in fossil plants of that kind. 



Chondrites gramiiiiformis. Sp. nov. — Fronds brittle, with few 

 dichotomous branches in acute angle of divergence, all exactly 

 linear by compression, more or less flexuous, generally broken in 

 short fragments ; surface covered vi^ith thin, smooth, coaly 

 pellicle. 



These fragments are numerous and very distinctly traced in 

 black upon the grayish-white and colored slabs, 1 to 1-^ mill, 

 broad, mostly short, from | to 3 cm. long, the longest fragment 

 preserved being a curved branch 5 cm. long. They are spread 

 upon the stone in every direction and in such a way that the 

 primary divisions of the frond cannot be recognized. For all 

 the fragments are simple, or with only a branchlet diverging in 

 a very acute angle near the top of a few ot them. 



The species has, by the form and mode of division of the 

 branches, the character of CJiondrites setaceus, Heer, a jurastic 

 species of Switzerland (Oxfordian), from which it differs merely 

 by the greater width of its branches, which are at least twice as 

 broad. The general appearance, mode of ramification, and text- 

 ure are the same. 



The species, as it is, may be easily represented to the mind by 

 the description and without figures. If, however, better speci- 

 mens should ever be obtained, it would be worth while to have 

 it figured carefully, especially to have a representation of the 

 basilar part of the frond. 



Fossil remains of true marine plants are of rare occurrence ; 

 for a large number of those which have been described as such 

 represent tracks or burrows of worms or of other marine animals. 

 These, however, are never covered by a carbonaceous layer. 



