155 



a. occidentalis, and that Hormotoma Winnipegensis of the same rocks 

 does to the eastern M. bellicincta. 



Protae^a vetusta, Hall. 



PoriUs ? wtesto, Hall 1847. Pal. N. York, vol. I., p. 71, pi. 25, 



figs. 5, a-h. 



Porites vetusta, Edwards and Haime ISSl. Mon. Polyp. Foss. Terr. Paleoz., p. 



208, pi. 14, figs. 6 and G a. 



,1 Nicholson 1875. Geol. Surv. Ohio, Palaiont., vol. II., 



p. 221. 



1875. Rep. Pal. Prov. Ont., p. 9. 



u ,1 Hall 1882. Eleventh Rep. St. Geol. Indiana, p. 



378, pi. 49, fig. 4. 

 n 11 Winchell and Sohuchert. . 1895. Geol. Minn., .Final Rep., vol. III., 



pt. 1, p. 94, pi. G., figs. 24 and 25. 



Little Black Island, Lake Winnipeg, J. B. Tyrrell, 1889 : one speci- 

 men, a little more than an inch in its maximum diameter, and about a 

 millimetre thick. 



Protae^a (vetusta? var.) magna. 



Plate 18, figs. 2, 3 and 3a. , 



Corallum large, attaining to a maximum diameter of at least six inches 

 and forming crusts from five to fifteen millimetres thick, on or around 

 other organisms such as corals or Orthooeratites. Calyces closely con- 

 tiguous, extremely shallow, about two millimetres in diameter, rounded 

 polygonal, but very indistinctly defined, the centre of each occupied 

 with a group of from five to seven minute tubercles. Septa about 

 twelve in number, short, wedge-shaped, and perhaps crenulated at their 

 summits. When the surface is slightly ground down and examined with 

 a lens the closely grouped tubercles in the centre of each calyx have 

 somewhat the appearance of a spongiose pseudo-columella. 



Transverse and vertical sections, if correctly interpreted by the writer, 

 shew that the entire corallum is composed exclusively of compact scle- 

 renchyma, consisting of a close aggregation of minute tubes which are 

 nearly uniform in size and extent from the base to the summit of the 

 organism, and that the calyces are mere shallow depressions of the surface 

 of this mass of sclerenchyma. Transverse sections through the calyces 

 shew that there are from three to six solerenchymatous tubes between 

 two closely adjacent calyces, and similar sections below the calyces exhibit 

 only a dense mass of minute sclerenchymatous tissue, composed of tubes 

 that are irregularly four to six sided. In longitudinal sections these 

 tubes are seen to be frequently rather flexuous and somewhat twisted 

 together. They are invariably filled with the matrix, but in some of 



