GRAPTOLITES OI' XEW YORK. PART 1 



715 



Fisr.SS Phyllograptus 

 anna Hall. Martfinal por- 

 tion of rhabdosome. lo show 

 the appearance of the thecal 

 apertures in tlie compressed 

 condition. Deep kill, xi.5 



Position and localities. In the last layei's of graptolite bed 2 (Tetra- 

 graptus horizon), and throughout the horizon with Didymograptus 

 b i f i d u s . Also in the next horizon with Dip log rapt us dentatus 

 as well at the Deep kill, as at Mt Moreno. In Canada this form has been 

 found, according to Hall and Lap worth, only in the 

 St Anne beds, representing there the horizon with 

 Didymograptus bifidus. Ami records it also 

 from an outcrop near the city hall of Levis, in association 

 with Didymograptus bifidus, etc. and from a 

 locality on the Chaudiere river. Grurley observed it also 

 in suites of graptolites from the Beekmantown beds of 

 Arkansas and Nevada. It is known from the Middle 

 Skiddaw slates of the Lake district of England, where it is found associated 

 with P. angnstifoHus; and from south Scotland. 



Remarhs. This form is easily recognized, as pointed out by Hall and 

 Elles, by its small size and the great number of thecae in a given unit of 

 length. This is greater than in any other species and goes, in the Deep 

 kill specimens, beyond the number obtained by the above cited authors. 

 The greater width of the end is also, though not an unfailing, yet a strik- 



 ing character of the majority of the specimens, and the 



acute slender form of the mucros serves also to distin- 

 guish this species from the associated forms; specially 

 from dwarfed specimens of P. ilicifolins, which 

 have been noticed in the material. 

 The specimens observed in the last horizon of the 

 Fig. 99 Phyiioerraptus Deep kill scctiou have a still more condensed aspect. 



anna Hall. Ashhill quarrv '^ ' 



at Mt Moreno. x5 " jjjgj^ thecae numbcr as much as 22 in the space of 



10 mm, and the total size attained is not more than 3.6 mm. They represent 

 clearly a last dwarfed and paracmic mutation of the species, which might be 

 designated as P. anna mut. ultimus [pl.l5, fig.29, 80]. 



In the beds with Diplograptus dentatus exposed at Mt Moreno 

 a form of P . anna is extremely common, which, while, by its outline, 



