THE EARLIEST PLANTS. 



793 



to the animal kingdom. There can be no question that some of these 

 are truly marine plants ; and that plants of this kind occur in forma- 

 tions older than those in which we tirst find land-plants, and that they 

 have continued to inhabit the sea down to the present time. It is 

 also true that the oldest of these algae closely resemble in form plants 

 of this kind still existing ; and, since their simple cellular structures 

 and soft tissues are scarcely ever preserved, their general forms are 

 all that we can know, so that their exact resemblance to or difference 

 from modern types can rarely be determined. For the same reasons it 

 has proved difficult clearly to distinguish them from mere inorganic 

 markings or the traces of animals, and the greatest divergence of 

 opinion has occurred in recent times on these subjects. 

 The author of this work has 



given much attention to these 

 remains, and has not been dis- 

 posed to claim for the vegetable 

 kingdom so many of them as 

 some of his contemporaries.* I 

 believe there are many real ex- 

 amples of fossil alga^, but the 

 difficulty is to distinguish them. 



The genus Buthotrephis of 

 Hall, which is characterized as 

 having stems, subcylindi'ic or 

 compressed, with numerous 

 branches, which are divaricat- 

 ing and sometimes leaf -like, 

 contains some true alga;. A 

 beautiful species, collected by 

 Colonel Grant, of Hamilton, 

 and now in the McGill College 

 collection, may be described as 

 follows : 



Buthotrephis Grantii, S. N. 

 (Fig. 5). — Stems and fronds 

 smooth and slightly striate lon- 

 gitudinally, with curved and in- 

 terrupted striai. Stem thick, 

 bifurcating, the divisions ter- 



niinatino" in irregularlv pinnate ^'**- ^•—Buthotrephlf GranfU. a nronnine Alga from 

 r ^ , the Silurian, Canada. 



fronds, apparently truncate at 



the extremities. The quantity of carbonaceous matter present would 

 indicate thick, though perhaps flattened, stems and dense fleshy fronds. 

 It may be well to mention the remarkable Cauda-Galli fucoids, 

 referred by Hall to the genus Spirophyton, and which are characteris- 

 * " Impressions and Footprints of Aquatic Animals," " American Journal of Science," 18T3. 



