(iUAITOLITES OF NKW YOKK, I'AUT 1 713 



D i p 1 o g r !i p t u « d e u t a t u s ) , specially in the lower part of the same, 

 exposed in the Ashhill quarry at Mt Moreno, Hudson, where it is very 

 common. Hall's types came from the shales of Point Levis ; but, as no 

 associated forms are mentioned, the horizon is not determinable fi'om his data. 

 Ami, however, cites it from several localities near Point Levis and Quebec in 

 association -with species of the zones of D id y inograp t us bifid us 

 and of Tetragraptus. It can be thus inferred 

 that, in the Quebec region as well as at the Deep 

 kill, it ranges thi'oujjh several zones. A similar 



JO o 



range of the species has been observed by Elles 

 and Wood in Great Britain. Also in Sweden 

 (Scania) it appears to be a form of the Tetra- 

 graptus horizon as \\ell as of the Phyllograptus 

 cf. typus zone. Brogger found it associated with nflT;fl^HU!'°»gd7i?*po7tioVo^tThil: 



._ -, . , . dosome enlartfed. Shows the shape of 



1. typus and numerous varieties or mutations the aiiertiires in compressed stat«. and 

 *' ^ the central canal. Deep kill. x4. 8 



of the two species, in the upper beds of the 



Phyllograptus shale of Christiania. Holm obtained his material from the 



gray Orthoceras limestone of Oelaud. 



Hemarhs. While this species persists beyond the range of P. ilici- 

 folius into the horizon with D i p 1 ogi'a p t u s den tat us, it begins 

 in the Tetragraptus beds, where P . i 1 i c i f o 1 i u s is prevalent, Avith forms 

 that possess the long linear outline of P . a n g u s t i f o 1 i u s and the 

 uniform direction and curvature of the thecae in the middle portion, a 

 characteristic that seems to be dependent on the narrow development oi 

 the rhabdosoine, while in the antisicular part the thecae are still more 

 ascending than in P. an g u s tif o liu s , but not so strongly as in typical 

 P. ilicifolius. The apertural mucros are not yet as strongly developed 

 as in the P. angustifolius from the higher horizon, but of the same 

 character, viz extensions of the lower maigins. Indeed from a comparison 

 of the drawings of the apertural extensions of P. angustifolius fur- 

 nished by Holm [text fig.94j with those of P . ilicifolius [text fig. 95], 

 it is to be inferred that they are of exactly the same character and diifer 



