FUCOIDES IN THE COAL FORMATIONS. 317 



This simplicity of structure, with some peculiar characters of the Fucoidal remains 

 under examination, seem to fix their relation with the Gaulerpce, a group of Chlorosperm 

 Algae of our time. " The fronds of these plants consist of prostrate primary stems {surculi), 

 rooting from their lower surface and throwing up erect branches or secondary fronds of 

 various shapes. Their substance is horny, membranaceous, destitute of calcareous matter, 

 their structure uncellular, the cell (or frond) continuous, strengthened internally by a 

 spongy network of anastomosing filaments, and filled with a semi-fluid grumous matter."* 

 The primary fronds or stalks of the species of this order are smooth and glossy, a charac- 

 ter particularly marked in Caulerpites marginatus of ours. For, on the limestone, even 

 when it has not been washed by the water of the creek, these stalks of a dull grayish color 

 are clearly defined, perfectly smooth, even shining or polished. The development of the 

 secondary fronds of the Caulerpae is multiform in the extreme, as can be expected in a plant 

 which is of the simplest structure and is formed by the continuous development of a single 

 cell, or is, so to say, nothing but a kind of bag of a flexible tissue. In Gaulerpa prolifera, 

 Lam., the secondary frond expands into a tongue-shaped, flat petioled, leaf-like division, 

 which is itself proliferous from any part of its surface. In other species the secondary 

 fronds are sometimes pinnately branching into elongated bladdery cylindrical appendages, 

 sometimes irregularly divided into ribbon-like branches, without any appearance of order. 

 Even in Caulerpa clavifera, Ag., these secondary fronds are more or less densely set all 

 around by scattered club- or top-shaped vesicular branchlets. The only character which 

 renders our fossil plant in some way different from the forms which we are accustomed to 

 find in this group of Alga?, is its eccentrical shape. But it is seen from plateVEJfig. 4, that 

 the secondary frond is not a second frond, implanted on or born from the primary one, but is 

 really a mere continuation by inflation of the stalk. This, expanding like a bladder, is 

 forced upwards, the division of the stalk forming the thickened or smooth border around 

 it. The stalks or surculi, as seen in figs. 5 and 6, are inflated in various ways, and may, 

 even after dilating into laminas, take again their tubular, more simple form, a disposition 

 which is seen also in some species of Cuulerpce. 



It is in consideration of those natural affinities, that I have placed the new species of 

 Fucoides of the coal in the genus Caulerpites of Sternberg ; and the same reasons would 

 induce me to admit into it all the related forms described by Prof. Hall under the name of 

 Spirophyton, as well as the peculiar Fucoides Serra described by Brongniart.t This last, 

 according to the remarks of that celebrated author, was found in the limestone of Transi- 



* Nereis Boreali Americana, by T. H. Harvey, vol. iii, p. 12. Most of the remarks concerning the Caulerpae 

 are taken from this admirable work. 



f Vegetaux Fossiles, p. 71, tab. G, figs. 7 and 8. 



