/ GRAPTOLITES. 113 
visible to having sometimes a length equal to one third the width of the 
stipe. Sometimes the margins of the stipes are entirely smooth and 
straight, and the flattened surface shows indentations produced by the 
cellules. Often the surfaces are so nearly smooth that these indenta- 
tions may be readily overlooked. In those flattened stipes where the 
margins are straight, or where only minute points are visible on the margin, 
the width varies from nine to eleven hundredths of an inch. 
In all well-preserved specimens, whatever the aspect of the cellules, the 
basal processes or radicles are nearly constant in presence and direction ; 
and the solid axis always projects beyond the upper end of the stipe, and 
sometimes to the extent of an inch beyond the celluliferous portion. In 
the extension of the cell-denticles upon the margins of the stipe, in the 
condition represented in fig. 12, the specimens bear some resemblance to 
Letiograptus. 
EXPLANATIONS OF FIGURES OF CLIMACOGRAPTUS ANTENNARIUS, Hall. 
Puate XIII. 
11. A young individual, compressed in such & manner that the cell-apertures are 
not shown upon the margin. 
12. A flattened stipe, presenting only the mucronate terminations of the cell- 
apertures beyond the margin. 
13. An older individual, showing the margins of the stipe extending beyond the 
cell-apertures, while the cellules are visible in the substance of the stipes 
as darker areas. 
Formation and Locality — Quebec group ; Point Lévis. 
Genus RETIOLITES, Barrande. 
Generic characters.—Stipes thin, flat, elongate, triangular, composed of 
two series. of cellules symmetrically arranged in regard to the axis of the 
figure. The cellules arise from a single internal canal which occupies the 
central portion of the stipe. The cell-orifices are disposed upon the sides 
of the triangle, making an acute angle with the axis, and leave no space 
between themselves. 
The above is essentially the description of this genus given by Mr. 
Barrande. 
The species from the Clinton group, which I have referred to this genus 
is extremely flattened, and it is not possible to determine that it has a tri- 
angular form. It possesses a very distinct axis and cell-divisions, which 
however may sometimes be concealed by the reticulate covering. In the 
