914 



PALEONTOLOGY OF NEW-YORK. 



from their appearance and relation to the serratures, I infer that they are of more 

 importance in the organization than simply as ornament. 



Grnptolithns divaricatn*. 



Fig. 1. A large individual, where the divergence of the parts is much greater than in figure 3. The 

 figures are twice the natural size of the specimens. 



Fig. 2. A part of the stipe still farther enlarged, showing the serratures and the small nodes. 



Fig. 3. An individual, where the divergence is less than 90 degrees. 



Fig. 4. A part of fig. 3 much enlarged, to show the form of the serrature. 



Geological position and locality. In the shales of the Hudson-river group : Nor- 

 manskill near Albany. 



Graptolitlins niarcidus ( n. s.). 



Frond simple, biserrate : stipe short, rigid; midrib strong; serrations 

 deep, the denticles small, triangular, subobtuse, arranged in the pro- 

 portion of twenty-eight to thirty-two in the space of an inch, often 

 somewhat alternating on opposite sides of the stipe, which is terminated 

 below by two or three longer denticles which are of the same substance 

 as the body of the stipe. The apex is marked by an extended fibre or 

 continuation of the axis. 



The specimens of this species which I have seen are usually not more than from 

 one-half to seven-eighths of an inch in length. The axis is narrow; the points of the 

 serrations separated, leaving a defined triangular indentation; and the aspect is 

 that of a contracted or shrunken stipe, and by this character alone is very readily 

 distinguished. It has been observed in considerable numbers, so that we can have 

 no doubt as to the constancy of its characters. 



