3IO TABULATE CORALS. 



strongly convex vesicles. From the nearly allied F. proporoides, 

 Nich., the present species is distinguished by its generally more 

 massive form, the inflections of the walls of the large corallites 

 above spoken of, and the fact that the tabulae of the smaller 

 tubes coalesce to form a vesicular tissue. 



Formation and Locality. Common in the Hamilton Group 

 of Arkona, Ontario. I originally included under the name of 

 Callopora incrassata certain large and massive specimens from 

 the Corniferous Limestone of Ontario. Not having had, how- 

 ever, the opportunity of examining these microscopically, I do 

 not feel sure they are specifically identical with the Hamilton 

 examples, upon the characters of which the foregoing descrip- 

 tion is based. 



Fistulipora proporoides, Nich. 

 (Fig. 41, and PI. XV., figs. 2, 2 a.) 



Spec. Char. Corallum in the form of thin and extended, 

 often much contorted expansions, which have an average thick- 

 ness of about one line, and have the under surface covered by 

 a concentrically -striated epitheca, the corallites being nearly 

 vertical, and opening upon the upper surface. The large coral- 

 lites are oval or nearly circular, about one-fifth or one-sixth of 

 a line in diameter, and separated by interspaces of about the 

 same width. The " small " corallites are markedly angular, 

 only one row ever existing between contiguous round tubes, 

 and their size being often equal to, or even larger than, that of 

 the latter. On the surface the calices of the round tubes 

 appear as marked projecting apertures, while the calices of the 

 angular tubes appear to be usually closed in the adult condition 

 by a thin calcareous membrane. Maculae present or absent. 

 In internal structure the round tubes have very few or no 

 tabulae, and, when present, these structures are always com- 

 plete and horizontal. The " small " tubes are always bounded 

 by complete walls, and are intersected by comparatively 

 numerous horizontal, not vesicular tabulae. 



