38 THE GEOLOGICAL HISTORY OF PLANTS. 



tinct evidence of the organic character of the wedge- 

 shaped fronds. It is from the Utica shale, and elsewhere 

 in the Siluro-Cambrian. It is just possible, as suggested 

 by Hall, that this plant may be of higher rank than the 

 AlgEe. 



The genus Palmophycus of Hall includes a great va- 

 i-iety of uncertain objects, of which only a few are prob- 

 ably true Algae. I have specimens of fragments similar 

 to his P. virgatus, which show distinct carbonaceous 

 films, and others from the Quebec group, which seem to 

 be cylindrical tubes now flattened, and which have con- 

 tained spindle-shaped sporangia of large size. Tortuous 

 and curved flattened stems, or fronds, from the Upper 

 Silurian limestone of Gasp6, also show organic matter. 



Kespecting the forms referred to LicropJiycus by 

 Billings, containing stems or semi-cylindrical markings 

 springing from a common base, I have been in great 

 doubt. I have not seen any specimens containing une- 

 quivocal organic matter, and am inclined to think that 

 most of them, if not the whole, are casts of worm-bur- 

 rows, with trails radiating from them. 



Though I have confined myself in this notice to plants, 

 or supposed plants, of the Lower Palaeozoic, it may be 

 well to mention the remarkable Cauda-Galli fucoids, re- 

 ferred by Hall to the genus Spirophyton, and which are 

 characteristic of the oldest Erian beds. The specimens 

 which I have seen from N^w York, from Gasp6, and 

 from Brazil, leave no doubt in my mind that these were 

 really marine plants, and that the form of a spiral frond, 

 assigned to them by Hall, is perfectly correct. They 

 must have been very abundant and very graceful plants 

 of the early Brian, immediately after the close of the 

 Silurian period. 



We come now to notice certain organisms referred to 

 Algae, and which are either of animal origin, or are of 

 higher gi'ade than the sea-weeds. We have already dis- 



