26 
thicknesses had been impressed. The delicate branches 7; 
inch in width count fifteen furrows to $ inch length. The 
stouter branches measuring ;%, inch have much _ broader 
transverse ridges. It is found in a 4-foot stratum of sand- 
Fic. 2. Arthrophycus elegans. 
stone, interstratified between two heavy strata of red clay, 
used for brick-making.—Coal Measures, Marietta, Ohio. 
Nodophycus thallyformis, a New Genus. 
(Plate I, Fig. 2.) 
The fronds of this seaweed must have been very large. 
I find them covering large slabs of sand-stone. The nodose 
elevations of the frond are from one-third to one-half inch 
apart and look as if a soft thallus had spread over peas.— 
Carboniferous Sand-stone, Marietta, Ohio. 
