20O TABULATE CORALS. 



Columnaria (?) Halli, Nicholson. 

 (PL X., figs. 3, 3 «.) 



Columnaria alvcolata, Hall, Pal. N.Y., vol. i. p. 47, PI. XII., figs. 1 a - c. 



,, alveolata, Billings, Geol. Can., fig. 70, p. 139, 1863. 



,, alveolata, Nicholson, Sec. Rep. Pal. Ont., p. 8, 1875. 



,, alveolata, Rominger, Foss. Cor. of Michigan, p. 89, PI. XXXIV., 



figs. I, 2, and 4, 1876. 

 (Non Columnaria alveolata, Goldfiiss.) 



Spec. Char. — Corallum forming large massive colonies, which 

 vary from a few inches to several feet in diameter, and which 

 are composed of variously- sized polygonal corallites, in close 

 contact with one another throughout their entire length. The 

 walls of the corallites are not excessively thickened, and they 

 are so completely amalgamated in contiguous tubes that even 

 under the microscope the original line of demarcation between 

 the tubes can be made out with difficulty or not at all. The 

 large tubes are usually from two to three lines in diameter, 

 though occasionally considerably more than this ; and the 

 smaller corallites are of all sizes. Septa marginal, in the 

 form of obtuse longitudinal ridges, which vary in number 

 from twenty to forty, do not extend to any distance into 

 the visceral chamber, and are not divisible into an alternat- 

 ing longer and shorter series. Tabulae strong, horizontal, 

 and complete, about half a line apart or sometimes closer. 

 Mural pores not recognised with certainty. 



Obs. — I have come to the conclusion, after full consideration, 

 that the best course to adopt with regard to this species is to 

 give it a distinct specific name, though it has so long been 

 known to palaeontologists as C. alveolata, Goldf, that this 

 course is attended with much inconvenience, and I have 

 myself elsewhere opposed it (Sec. Rep. Pal. Ont., p. 8). 

 Dr Rominger has evaded the difficulty, as I tried to do 

 by reserving the name of C. alvcolata for the form now 

 under consideration, and by retaining Hall's Favistclla stel- 

 lata. It is, however, quite certain that the latter is really 



