GRAPTOLITES. 141 
EXPLANATIONS OF Figures or Prinograptus GeErniTzianus, Hall. 
Puate XXI, 
A branching fragment showing the celluliferous side. 
A fragment which is irregularly branched, showing the non-celluliferous side. 
A single branchlet of the same species. 
An enlargement from fig. 5, showing the cell-apertures. 
DTD % 
Formation and Locality —Shales of the Quebec group; Point Lévis. 
Genus THAMNOGRAPTUS, Hall. 
Gr. Oauvos, frutex, and ypadw, scribo. 
(THamnocraptvs, Pal. N. Y., Vol. III, p. 519,* 1859.) 
Generic characters —Fronds consisting of straight or flexuous stipes 
(growing singly, or conjoined in groups at the base ?), with alternating or 
widely diverging branches: branches long, simple or ramose, in the same 
manner as the stipe. Substance fibrous or striate; the main stipe and 
branches marked by a central longitudinal, depressed line, indicating the 
axis. Cellules or serratures unknown. 
THAMNOGRAPTUS ANNA, Hall. (n. s.) 
Plate X XI, figure 9. 
Déescription.—Stipes slender, linear, undulating. Branches filiform, long, 
flexuous, regularly alternating on opposite sides: the distance between the 
branches on the same side is about fifteen hundredths of an inch, giving half 
that distance on the main stipe between the origin of the branches. At 
the base of each branch, the stipe diverges in the opposite direction, 
making an angle of 30° with its previous direction. The angle between 
the stipe and the branch measured on the lower side is about 130°, and on 
the upper side 80°, showing a divergence of 30° in the direction of the 
stipe. . 
* A description of this genus, with other graptolitic genera, was read before the 
American Association for the Advancement of Science, at Baltimore in 1858; but the 
paper was not sent infor publication, and only a newspaper report of it was given. 
