Genus Graptolithus. . 167 



Graptolithus pristiniformis. 



Description. — Stipe simple, witli serratures on both sides ; ser- 

 ratwes closely arranged, very oblique, acute, mucronate ; thirty- 

 two in the space of an inch. 



This species approaches to G.pristis (Pal. N.Y., vol L, p. 265, 

 pi. 72, fig. 1), but the serratures are more ascending, and the ex- 

 tremities more distinctly mucronate. The specimens observed 

 however, are imperfect fragments, which are very closely com- 

 pressed, being barely a film upon the surface of the shale, and the 

 determination is somewhat unsatisfactory. 



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



Collector. — J. Richardson. 



Graptolithus ensiformis. 

 ( Genus Retiolites ? Barrande.) 



Description. — Stipe simple, sub-ensiform or elongate-spatulate, 

 usually broader in the middle and narrower towards the extremi- 

 ties ; a central rib, with strongly marked obliquely ascending striae 

 which reach the margins ; serratures obscure, apparently corres- 

 ponding to the striae ; margin usually well defined. 



Several specimens of this form occur on a single slab of slate, 

 associated with G. tenaculatus and G. quardribrachiatus. The 

 oblique strise apparently indicate the direction of the serratures, 

 and in one specimen there is an appearance of obtuse indentations 

 upon the margin ; but it is scarcely possible at the present time to 

 define satisfactorily the character of these serratures. In form and 

 general character this species differs from all the others sufficiently 

 to be readily distinguished. 



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



Collectors. — J. Richardson, Sir W. E. Logan, James Hall. 



Graptolithus tentaculatus. 



(Gensus Retiolites, Barrande.) 



Description. — Stipe simple, linear, elongate-lanceolate or some- 

 times elongate-ellipticle when entire ; mid-fib double, extending 

 much beyond the apex of the frond ; exterior margins when en- 

 tire, reticulate and armed with mucronate points, (and with mu- 

 cronate points alone, or smooth, when imperfect,) with an extend- 

 ed setiform tentacle-like process from each side of the basal extre- 

 mity ", substance of the centre reticulate or cellular! 



