164 Hall on the 



or depressed line extends from the base of the serrature obliquely 

 towards the base of the branch, and at its termination the surface 

 of the branch is marked by a minnte but distinct round tubercle. 



This beautiful little species differs very distinctly from any others 

 of this genus, in the thickened substance of its branches, the close- 

 ly arranged serratures, and the minute tubercles at the base of 

 the grooves or striae. The specimens usually preserve consider- 

 able substance, and are far less flattened than most of the other 

 species, owing either to their original character or to the nature 

 of the surrounding matrix. The impressions of the oblique lines or 

 striae are often well preserved in imprints of the fossil left in 

 the slate. 



The impressions of G. bryonoides resemble those of this species ; 

 but the branches are broader, and the striae are less rigid and less 

 distinctly impressed, while the absence of tubercles, and the coars- 

 er serratures, when visible, at once serve to distinguish the species. 



In mode of growth and general aspect this species resembles 

 the G. serratulus (Pal. N. Y., vol. 1, p. 274, pi. 74, fig. 5, a, b.) 

 of the Hudson River shales ; but in the latter the serratures are 

 coarser and more oblique, the lower side being much the longer. 

 The branches of that species are also more distinctly linear, while 

 in this they become gradually wider from the base, and are very 

 distinctly striate and tuberculate in well-preserved specimens. 



The preceding description applies to the specimens of this spe- 

 cies where the branches diverge abruptly, or nearly at a right angle, 

 from the radicle. 



Locality and Formation. — Point Levy, Hudson River Group. 



Collector. — J. Richardson. 



Graptolithts bifidus. 



Description. — Two-branched ; branches very gradually and 

 uniformly diverging from the base to the extremities ; surfaces 

 obliquely striated ; serratures moderately oblique ; extremities 

 often nearly vertical to the rachis, and submucronate (?) ; from 

 thirty-eight to forty in the space of an inch ; radicle short. 



This species resembles in general features the G. nitidus, and 

 rnio-ht be mistaken for that species with the branches approxi- 

 mated by pressure. In several individuals examined the serra- 

 tures are much closer, being from six to eight more in the space 

 of an inch, while the general form is constant. The outer mar- 



