No. 186.] 



57 



Fig. 8. The specimen, natural size. 



TO 



Graptolithus multifasciatus. 



Graptolithus divergens ( n. s.). 



Body slender, consisting of a straight central stipe or rachis ; on each side 

 of the longitudinal centre of which are given off diverging branches in 

 pairs, and nearly opposite each other at the bases : these branches are 

 of unequal length, the longest being frequently as long as the main stipe 

 on either side of its centre. Branches slenderly serrate on one side. 



Fig. 9 is an individual of this species, one branch of which 

 appears to bifurcate near its origin. 



These species are from the shales of the upper part of the Hudson-river 

 group. 



Graptolithus gracilis. 



The accompanying figure is of a very beautiful specimen of the G. 

 gracilis, first described in the Palaeontology of New- York, Vol. i, p. 274. 

 The specimens of this species all present the peculiarity of having a 

 slender sinuous rachis, approaching in form the letter S, from which the 

 branchlets diverge always on the convex side of the curve, so that ordina- 

 narily one half the branchlets proceed in one direction and the other half 

 in the opposite direction ; and although there has been observed no mark 

 of a radicle or central point, it seems probable that the place from which 



[Assembly No. 186.] 8 



