68 
AUG. F. FOERSTE 
a thin carbonaceous film, the reticulating fibers being distributed 
through a visible thickness of the matrix, though possibly scarcely 
a 0.1 mm., in this dimension. The reticulation of the fibers of 
the frond can be recognized locally. The hair-like fibers extend 
2 mm. beyond the margin of the frond. They arise apparently 
from black dots on its flat surface. 
In specimen 19 the rachis-like film is 0.5 mm. wide. The 
reticulated structure of the fibers forming the body of the frond 
is visible. From 4 to 6 hair-like fibers occur in a width of 0.5 
mm. along the margin of some of the lobes. From 6 to 7 dots 
may be recognized in a length of 0.5 mm. along some of these 
fibers. 
In specimen 21 A the rachis-like film, 0.5 mm. wide, is distinctly 
shown, and the series of dots belonging to the fibers along the 
margin of some of the lobes are distinctly visible. Of the larger 
black dots, 6 or 7 occur in 1 mm. 
In specimen 25 the median rachis-like film is 0.4 mm. wide; 
the corresponding structures of the lateral lobes are far less 
distinctly outlined. The appearance of reticulation among the 
fibers forming the frond is strikingly shown. Some of the meshes 
are 0.4 mm. long and 0.2 mm. wide. On close examination 
many of these fibers appear to be supplied by a series of dots, 
varying from 5 to 7 in a length of 0.5 mm. Some of those near 
the margin of the frond serve as points of attachment for the 
hair-like fibers. At one point numerous hair-like fibers may be 
traced for almost 3 mm. beyond the margin of the frond. They 
are shown best near B as located on plate 'IX. 
Buthotrephis Hall 
The genus Buthotrephis was founded by Halb^ on Buthotrephis 
tenuis Hall, from the Trenton of New York, and not on Butho- 
trephis antiquata Hall, from the Chazyan of that state. This is 
evident from his statement in the description of Buthotrephis 
antiquata that “In the present genus, the typical form is to be 
found on plate 21, fig. 1,’’ where the genotype is erroneously 
Hall, James, Paleontology of New York, vol. 1, p. 8, 1847. 
