162 Hall on the 



companying its imbedding in the rock. The specimen exhibits 

 the inner or serrated side, and the branches are turned so as to 

 be compressed laterally at a distance of two inches or more from 

 the centre ; one of the branches presents a length of nearly 

 seven inches from the centre. This species is named after its dis- 

 cover, Mr. John Head. 



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



Collectors. — Mr. John Head, and Sir W. E. Logan. 



Graptolithus alatus. 



Description. — Frond composed of four branches; disk much 

 extended along the sides of the branches, giving them an extreme- 

 ly alate character; branches strong, angular on the lower side; 

 upper or serrated side unknown. Some indentations on the ex- 

 terior side of the branches, which may indicate the place of serra- 

 tures on the opposite side are about one twenty-fourth of an inch 

 distant. 



The only specimen of this species yet recognized is a part of the 

 disk with three of the branches, two of which present the corneous 

 expansion apparently entire, extending about two inches from the 

 centre along the branches, while its margin in the indentation be- 

 tween the branches is not more than three eighths of an inch from 

 the centre. This species is much more robust than G. quadribrachi- 

 atus or G. bryonoides, and the form of the disk when preserved 

 will always be a distinguishing feature. 



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



Collectors. — Mr. John Head, and Sir W. E. Logan. 



Graptolithus fruticosus. 



Description, — Branches bifurcating from a long slender filiform 

 radicle, and each division again bifurcating at a short distance 

 above the first; branches and branch lets short, narrow linear; 

 serratures apparently commencing in the lower axil, where there 

 are one or two between the first and second bifurcations. Serra- 

 tures somewhat obtuse at the tip ; lower side longer, upper margin 

 nearly at right angles to the rachis ; about sixteen serratures in 

 the space of an inch. Substance of the branches thin, fragile. 



In one specimen the position of the serratures is such as to 

 present elongate acute apices in one of the branches. 



This species has the general habit of G. nitidus and G. bryo- 

 noides, but is very distinct in its long slender radicle, narrow fra- 



