SPENCER NIAGARA FOSSILS. 5S1 



ii)g branches overlie each other, or are united at points of contact 

 to form a net-work, with fine, more or less irregular, rhomboidal 

 interstices. The branches unite at base into a slender non-cellu- 

 liferous axis which terminates in a bulbous root. The striae along 

 the branches (which vary in thickness from a quarter to a third of 

 a millimetre) appear to mark the depressions of the common ca- 

 nal between the original positions of the polypites. The orifices 

 of the cellules have an ellipsoid form, and there are about four of 

 these for every millimetre of length. On the side of the stipe 

 opposite to the cellules there is a solid axis. In some specimens 

 there are occasional spine-like projections which are probably 

 rudimentary branchlets. The texture is corneous, although this 

 is sometimes replaced by pyrites. The typical specimen is about 

 five centimetres high. 



Formation and Locality. — This species was found by Col. Grant, 

 near the base of the " chert-bed" of the Niagara dolomite, at the 

 "Jolly-cut," Hamilton, Ont. 



Genus ACANTHOGRAPTUS. 



Gr. akantha, a tliorn ; grapJio, I write. 

 Genus Acanthograplits (Spencer). Can. Nat., vol. viii., No. 8, 1879. 



Fond shrub-like, consisting of thick branches, principally rising 

 from near the base, with little divergence and some bifurcations. 

 One side of the branches, furnished with prominent spines or 

 denticles, appearing to mark the position of the apertures of the 

 cells. Texture corneous, and indistinctly striated longitudinally. 



This generic form resembles some species of Dendrograptus^ 

 but the branches are stronger and more bushy than those of the 

 species of that genus, and have conspicuous spines, in whose 

 axils the cellules were probably situated. 



ACANTHOGRAPTUS GRANTI, nOV. Sp. 



Plate 4. Fi^. 5. 



Acanthograptus granti (Spencer). Can. Nat., vol. viii., No. 8, 1S7S. 



Frond shrub-like, with thick branches principally originating 

 near the base. Some of the branches bifurcated with dichoto- 

 mous terminations ending in free points. Cell-apertures conspicu- 

 ous on one side only, and situated in the axils of the prominent 

 spines. Surface longitudinally striated. Occasionally there are 



