SPENCER NIAGARA FOSSILS. 593 



versed by a central cylindrical, smooth, solid axis surrounded by 

 their common canal, which is sometimes only represented by a 

 central depression or elevation, but occasionally its form is weW 

 preserved. The rarely-indicated cell-openings are represented 

 by minute oval depressions in the substance. The texture is 

 highly corneous (or replaced by pyrites). 



The diameter of the frond is two centimetres, and of the disc 

 one centimetre ; the radiating branches extend half a centimetre 

 beyond the disc, and number between twenty-five and thirty, but, 

 as each is divided, the frond is surrounded by about sixty points. 

 The branches (both through the disc and free portion) are rather 

 over half a millimetre broad, but the terminals are scarcely more 

 than half that thickness and end in sharp points. 



Formatioti and Locality. — This perfect little species was found 

 in the dolomite of the Niagara formation proper, near the base 

 of the series, at the quarry just west of the "Jolly-cut road," at 

 Hamilton, Ontario. 



PART II. 



STROMATOPORID^ OF THE UPPER SILURIAN SYSTEM. 



After the Graptolites of the Niagara formation there are, per- 

 haps, no more interesting fossils than the Stromatoporidas. Of 

 this Family, six species (of which four are new) are found at 

 Hamilton, Ontario, and one new species at Dalhousie (on the 

 Ristigouche river), New Brunswick, all of which are herein de- 

 cribed and figured. 



The following is a list of these species : 



Stromatopora concentrica (Goldfuss), 

 Caunopora -walkeri (Spencer), 



" mirab ill's (Spencer), 



Caenostoma constellatum (Hall), 



" ristigouchense (Spencer), 



" botryoideum (Spencer), 



Dictyostoma reticulatum (Spencer). 



Besides these species, there are found in the Upper Silurian 

 system the following species : 



