GitArToi.rri:s of new youk, taut i 70^ 



Phyllograptus typus Enlgger. Die sil. Etagen 2 and 3. 1882. p.41 



Ph yllogr apt us of. typus TuUbefg. Skanes Grapt. in Sver. Geol. Und. Afli. 



och npps. ser. C, no. 50. 1882. p.21 

 Phyllograptus typus Malaise. Ann. de la Soc. Geol. de Belg. 1888. t.1.5, bul. 



p.42 

 Phyllograptus typus Ami. Geol. Sur. Can. Rep't. 1889. v.3, pt 2, p.50k ff 

 Phyllograptus typus Gnrley. Jour. Geol. 1896. 4:294 

 Ph y 1 lo g r a pt u s typus Roemer & Freeh. Lethaea palaeozoica. 1897. 1:005 

 Phyllograptus typus Elles. Quar. Jour. Geol. Soc. 1898. 54:494f 

 Phyllograptus of. typus Elles & Wood. Monogr. Brit. Grapt. pt 1. Pal. 



Soc. vol. for 1902. p.99, pi. 13, fig.5a,b 

 Phyllograptus typus Ruedemaun. N. Y. State Paleontol. Ann. Rep't. 1902. 



p.566 



This species, which, both by the gigantic size and the great variability 

 of its individuals, marks the acmic stage of development in the short lived 

 genus Phyllograptus has l)een fully described by its author and lately by 

 Elles and Wood. From these descriptions and the matei'ial in hand we 

 derive the followiuii- enumeration of the distinctive features of the 

 species. 



Description. The rhabdosome is exceedingly variable in relative length 

 and width, or in outline generally. Hall described it as being " elongate 

 ovate or lanceolate, broad oval or obovate," and Miss Elles's extensive measure- 

 ments demonstrate that in the Skiddaw specimens, the variations extend from 

 long and narrow forms, whose relative length and width are 57 and 6.3 mm, 

 to short and broad forms with 25.4 and 8.7 as corresponding figures. 

 Our material does not quite reach these extremes, but still illustrates well 

 the lack of fixation of the outline, and specially the frecpient occurrence (tf 

 lanceolate forms and the tendency of the rhabdosome to attain its maximal 

 width in the sicular half. 



The thecae are in contact throughout their length, number 9 to 10 in 

 10 mm, and are curved in all parts of the rhabdosome, viz in the sicular 

 portion slightly upward, which curvature lessens toward tlie middle portion 

 and finally assumes an obliquely upward direction in the antisicular portion. 

 The a^jertures are but slightly mucronate. 



