148 Hall on the 



ginated from the same point. A careful examination however will 

 show a little intervening space, and in one individual in its young 

 state this feature is very characteristic. 



The disk is a thick carbonaceous film, much stronger and coars- 

 er than in any of the preceding species, and corresponding in 

 this respect to the stronger branches. It is moreover variable in 

 form and extent in different specimens, and does not always appear 

 to be in proportion to the size of the branches. 



All the specimens yet examined present the exterior surface, so 

 that the celluliferous face of the arms has not been seen. An 

 impression of a short fragment of that surface of one of the bran- 

 chlets shows strong, deep indentations. The vigorous aspect of 

 this species contrasts with all others in this collection. In one 

 specimen, where the frond is imperfect, one of the arms extends 

 to a distance of more than eight and a-half inches from the 

 centre, while two others are more than six inches each, and 

 these are all broken at their extremities. 



In its long linear branches, this species resembles the G. Sagit- 

 tarius (Hall, Pal. N. Y., Vol. I., pi. 74, fig. 1, perhaps not the 

 European species of that name), but the branches are stronger 

 and the serrations coarser ; it is moreover associated with a group 

 of species, all or nearly all of which are quite distinct from those 

 of New York with which the G. Sagittarius occurs. 



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



Collectors. — J. Richardson and E. Billings. 



Graptolithus octonarius. 

 Description. — Frond composed of four principal branches, two 

 diverging from each extremity of the short, vinculum ; each 

 branch equally subdivided near the base, giving eight branchlets 

 which continue simple to their extremities ; branchlets gradually 

 expanding from the base ; serratures slightly inclined and trun- 

 cated above almost rectangularly to the direction of the serratures 

 and oblique to the rachis, giving a slightly obtuse extremity ; 

 about twenty-four in the space of an inch ; substance of the 

 branchlets thick ; divisions between the cells marked by a strongly 

 depressed line which extends from the base of the serrature down- 

 wards as far as the second serrature below, ending near the back 

 or lower side of the branch. 



The branchlets of this species resemble those of G. bryonoides, 

 and the distance of the serratures is almost the same, while in 

 some well-preserved specimens the obliquity of these parts is 



