Silurian and Devonian Fossils of Canada. 421 



corallites with an average diameter of about half a line ; transverse 

 diaphragms from four to six in a line ; radiating septa rudimentary, 

 but distinctly striating the interior walls. 



Formation and Locality. — Hudson River group ? Snake Is- 

 land and Traverse point, Lake St. John. 



Collector. — J. Richardson. 



Columnaria Blainvilli (Billings). 



Description. — Forming large sub-globose pyriform or hemis" 

 pheric masses of polygonal corallites one line and a-half in dia- 

 meter ; about eighteen radiating septa which reach the centre ; 

 transverse diaphragms three or four to one line. 



The radiating septa in fractured specimens where the interiors 

 of the tubes are well exposed, striate the surface exactly as in 

 Columnaria alveolata, from which species and from Favistella 

 stellata, Hall, it only differs by its smaller size. 



Formation and Locality. — Hudson River Group. Snake Is- 

 land, Lake St. John. 



Collector. — J. Richardson. 



Columnaria rigida (Billings). 



Description. — Forming large masses of polygonal corallites 

 usually three lines in diameter, but with numerous smaller ones, 

 and occasionally others of a larger size ; radiating septa, about 

 twenty, not reaching the centre ; transverse diaphragms from two 

 to four in one line. 



This species also resembles C. alveolata, but differs in the 

 greater development of the radiating septa which extend about 

 half-way to the centre. The tubes are also about the same size as 

 those of Favistella stellata, Hall, which differs in the septa not 

 only reaching the centre, but also in their often being so strongly 

 developed there, as to produce by their junction the appearance 

 of a pseudo-col umella. 



Formation and Locality. — Hudson River group ? Lake St. John. 



Collector. — J. Richardson. 



Columnaria erratica (Billings). 

 Desertion. — Forming large masses of corallites either in con- 

 tact or separate. The separate cells are round, those in contact 

 more or less polygonal, the radiating septa rudimentary, forming 

 about four sulci in the breadth of one line upon the interior ; dia- 

 meter of corallites from two to five lines, in general about three 



