172 Hall on the 



sometimes been filled and distended with, mineral matter before 

 imbedding, are very conspicuous. In a few instances the cells of 

 the lateral portions are filled in the same manner, presenting the 

 character of curving, conical tubes, with the broader extremity 

 outwards. 



The condition of preservation in several species examined is such 

 as to render unavoidable any other conclusion as to their mode of 

 growth than the one I have given above, however anomalous it 

 may seem. This species differs from P. typus in its thicker sub- 

 stance, proportionally shorter and broader form, and more closely 

 arranged serratures. 



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



Collector.— -J. Richardson. 



Phyllograptus angustifolius. 



Description. — Frond elongate-elliptical or elongate-lanceolate, 

 closely serrated ; serratures furnished with mucronate extensions, 

 about twenty-four in the space of an inch ; mid-rib broad, smooth ; 

 radicle scarcely preserved. 



This species is readily distinguished from either of the preceding 

 by its narrow and elongate form. The individuals examined are 

 very numerous, but being for the most part upon slaty laminae, 

 which are extremely compressed, they preserve scarcely any sub- 

 stance ; a mere outline with a more brilliant surface being almost 

 the only remaining character by which they are recognized. 



The individuals of this species are, in several specimens, equally 

 abundant with those of Phyllograptus typus. The mucronate 

 extensions upon the margins of this species are not so abrupt 

 as in P. typus and P. tlicifolius, the substance of the cell margin 

 being more extended along the mucronation. The number 

 of serratures upon each side of the frond varies according 

 to the size of the individual, being ordinarily from eleven or 

 twelve to twenty-four, while in a single individual of nearly 

 two inches in length there are forty-three or forty-four on 

 each side. The mid-rib in this species though broad, like those of 

 the preceding species, is not conspicuously serrate in any of the 

 specimens examiued. This feature however may have been obli- 

 terated by pressure. 



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



Collector. — J. Richardson. 



