GKAPTOLITES OF NEW YORK, I'ART 1 711 



HemarTcs. According to EUes this species is characterized by (1) the 

 number of thecae in a given unit of length, (2) the form of the aperture, 

 which is equally extended at its upper and lower limits. These characters 

 serve specially to distinguish the narrow variation of P . t y p u s from 

 P . a n g u s t i f o 1 i u s , ^vhich has more closely arranged thecae, and longer 

 apertural mueros, which are extensions only of the lower part of the 

 apertures giving the latter an oblique direction. Also, the character of the 

 curvature of the thecae and, specially, the direction of those of the 

 antisicular portion furnish a means of distinction of P . t y p u s from 

 P. angustifolius. 



P. ilicifolius exhibits, in the Deep kill section, a variability of 

 form similar to that of P . t y p u s . It also possesses a similar character 

 of curvature of the thecae, but has corresponding to its generally smaller 

 size, more closely arranged thecae, and, besides, longer and differently 

 shaped apertural mueros. P . t y p u s and ilicifolius, though not 

 mentioned by Hall as occurring in different associations are in their principal 

 development, separated in the Deep kill section, where P. ilicifolius 

 precedes P . t y p u s . 



Phyllograptus angustifolius Hall 



Plate 15, flsrures 31-34 



Pliyllograptus angustifolius Hall. Geol. Sur. Can, Eep't. for 1857. 1858. 



p. 139 

 Phyllograptus angustifolius Salter. Quar. Jour. Greol. Soc. 1863. 19:137, 



fig. 7a, L 

 Phyllograptus angustifolius Hall. Geol. Sur. Can. decade 2. 1865. p.l25, 



pl.16, fig.17-21 

 Phyllograptus angustifolius Nicholson. Quar. Jour. Geol. Soc. 1868. 



24:132 

 Phyllograptus angustifolius Linnarsson. Sver. Geol. Und. 1879. Afh. 



och upps. ser.C, no. 31. p.5 

 Phj'llograptus of. angustifolius Tullberg. Sver. Geol. Und. 1882. Afh. 



och upps ser.C, no.50. p.22 



