SPENCER NIAGARA FOSSILS. 59I 



Genus PTILOGRAPTUS (Hall). 



Gr. ptilon, a feather; grapho, I write. 



(Canadian Organic Remains, decade 7, 1865.) 



"Frond plant-like, rooted(.^), simple, or branching. Branches 

 and branchlets plumose, the pinnules rising alternately on op- 

 posite 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." 



Of this genus, the following beautiful species is preserved in 

 the rocks of the Niagara formation at Hamilton, Ontario : 



Ptilograptus foliaceus (Spencer). 

 Plate 6. Fig-. 7. 

 Ptilograptus Joliaceus (Spencer). Can. Nat., vol. viii., No. 8, iS7S. 



Frond bipinately branching. Slender branches plumose, with 

 delicate pinnules rising alternately from the opposite sides of the 

 branchlets. There are angular cell-openings on one side of the 

 pinnules, whilst on the other there are indistinct corrugations. 

 The substance is highly corneous. 



There are usually three or four branches originating from near 

 the same place on the short stipe, giving a lobed appearance to 

 the frond. On these numerous parallel pinnules are situated on 

 both sides of the axis (sometimes as many as sixteen, the branches 

 being rather more than a centimetre long), and on the lower sides 

 of these branchlets the cell-denticles occur. (There are two cells 

 and two intercellular spaces in the length of a millimetre. The 

 pinnules seldom exceed half a centimetre in length, and rise at 

 very acute angles. The slender branchlets are about one-third of 

 an inch thick. Even if the branches are separated, they are easily 

 recognized by the pinnules being regularly arranged. The whole 

 frond is never more than two centimetres wide. 



This species bears a resemblance to P. plumulosus of the Q_ue- 

 bec group, though much smaller and with fewer pinnules. 



Formation a?id Locality. — This beatiful little fossil, one of the 

 most perfectly preserved species of the group, occurs in the Nia- 

 gara dolomites at Hamilton, Ontario. 



