16 BULLETIN 65, UNITED vSTATES NATIONAL MUSEUM. 



Genus PTILOGRAPTUS Hall. 



Ptilograpiufi Hall., Geol. Suiv. Canada, Decade 2, 1865, p. 130; 20th Kep. 

 New York State Cab. Hist., 1S68, p. 218 (rev. ed., 1868 [1870], p. 252).— 

 ZiTTEL, Handbuoh d. Pal., I, 1879, p. 289. — Spencer, Trans. Acad. Sci. 

 St. Louis, IV, 1884, pp. 563, 591; Bull. Mus. Univ. State Missouri, I, 

 1884, p. 41.— Miller, North Amer. Geol. and Pal., 1889, p. 201.— Pocta, 

 Syst. Sll. Centre Bohemo, VIII, Pt. 1, 1894, p. 201.— Wiman, Natural 

 Science, IX, 1896. p. 246. — Roemer and Frech, Leth. geog., I Theil, 

 Leth. Pal.. I. 3 Lief., 1897, p. 579.— Ruedemann, New York State Mus., 

 MenL 7, 1904, p. 587. 



Ptilognipsiis Nicholson, Ann. and Mag. Nat. Hist. (4), I, 1868, p. 239; 

 Mon. Brit. Graptolitidte, 1872, p. 126. 



The generic characters of Ptilograptus were given by Hall (1865) 

 as follows: 



Frond plantlike, rooted? simple or branching. Branches and branchlets 

 plumose, the pinnules rising alternately on opposite sides of the branches: 

 celluliferous on one face only; branches cylindrical or flattened. Substance 

 corneous, dense; apparently smooth exteriorly, or corrugated by compression or 

 during fossilization. 



Genotype. — Ptilograptus phnnosus Hall. Tetragraptiis zone of 

 Quebec group in Canada. 



PTILOGRAPTUS FOLIACEUS Spencer. 



PtUograpsits foliaccus Spencer, Canadian Nat., VIII, 1878, pp. 458, 462. 



Ptilograptus foliaccus Spencer, Trans. Acad. Sci. St. Louis, IV, 1884, pp. 

 565, 591, pi. 6, fig. 7; Bull. Mus. Univ. State Missouri, I, 1884. pp. 15, 

 41, pi. 6, fig. 7.— Miller, North Amer. Geol. and Pal., 1889, p. 201, fig. 

 210.— GrKLEY, Journ. Geol., IV, 1896, pp. 100, 309. 



The original description is as follows : 



Frond bipinnately branching. The slender branches are plumose, with deli- 

 cate pinnules rising alternately from the opposite sides of the branchlets. There 

 are angular openings on one side of the i)innules, 

 whilst on the other there are indistinct corrugations. 

 When viewed from the face, the cellules appear as oval 

 impressions. 



The branches seldom exceed more than half an inch 

 in length and all appear to originate from nearly the 

 same place on the axis. From these numerous parallel 



„ ,o T. pinnules occur on each side of the axis (sometimes as 



Fig. 18. — Ptilograptus ^ 



FOLIACEUS Spencer, many as sixteen). The pinnules seldom exceed the 



The type - specimen fourth of an inch [5 mm; 1884] in length and rise at 



and a branch en- ^ ^.gj.y acute angle [by the pinnules being regularly 



larged. (After Spen- ■.-r.f^^ni-.'.j- xi i v,* i 



^ arranged; 1884]. Even if separate branches be found 



they are easily recognized. They appear to have been 



attached, but from the specimens before me the radicle seems to have been 



bi'oken off. 



Like the other members of this group the texture is corneous, but sometimes 

 replaced by i)yrites. This species closely resembles the P. phimuJosa of the 

 Quebec group, but is smaller (three- fourths of an inch) and finer in structure, 

 with the relatively [fewer and; 1884] longer pinnules. 



It occurs in the Niagara limestone at Hamilton, Ontario. 



