lambe ] CANADIAN PALAEOZOIC CORALS. 109 



Streptelasma robustum, Whiteaves. 



Plate VII., fig. 1. 



Streptelasma cor niculum (?) Hall. Large and robust variety. Whiteaves. 1881. Rep. 



of Progress for 1879-80, Geol. Survey of Canada, p. 57c. 

 Streptelasma robustum, Whiteaves. 1896. Canad. Rec. Sci., vol. VI., p. 391. 



Whiteaves. 1897. Palseoz. Foss., vol. III., pt. III., p. 153, pi. 



XVIII. , figs. 1, la. 



11 Corallum simple, elongate conical, usually rather strongly curved, 

 though some specimens are not so much curved as others, very large for 

 the genus, attaining to a length of seven inches as measured along the 

 curve of the convex side, to a height of nearly five inches, and to a 

 breadth or width of nearly two inches and a quarter at the summit. In 

 some adult or nearly adult specimens the sides are so much compressed 

 (perhaps abnormally so) that the convexly arched region is obtusely 

 angulated in the centre, longitudinally ; in some young specimens this 

 region is distinctly flattened, but others are circular in outline in trans- 

 verse section, or as seen from above. Septa^alternately long and short, 

 varying in number in large specimens from one hundred and sixty to one 

 hundred and seventy in all, the longer ones extending to the centre at 

 the bottom of the calyx. Surface marked with transverse wrinkles and 

 numerous fine striae of growth in well-preserved specimens, but often so 

 much worn, apparently prior to fossilization, as to be almost smooth. 



" Longitudinal sections through the centre of large specimens show that 

 the calyx is not very deep, and that its cavity occupies, but a small pro- 

 portion of the entire length. Below the calyx the corallum is filled with 

 strongly developed and apparently thickened septa, with well-marked 

 dissepiments^ between them, and these septa, with their dissepiments, 

 unite in the centre in such a way as to form a large irregularly reticulated 

 pseudo-columella, which projects slightly above the centre of the base 

 of the calyx, as a boss of irregular shape, but with a narrowly rounded 

 summit. 



" This fine coral is especially abundant, and attains to a large size in 

 the Red River valley, at Lower Fort Garry and East Selkirk, Manitoba, 

 where it was collected by Dr. R. Bell, in 1880, by T. C. Weston and A. 

 McCharles in 1884, by L. M. Lambe in 1890, and by D. B. Dowling in 

 1891. 



" On the western side of Lake Winnipeg a few comparatively small and 

 very imperfect specimens, which may be referable to this species, were 

 collected at Deer Island by T. C. Weston in 1884, at Little Black Island 

 by J. B. Tyrrell in 1889, at Jack Head and Snake islands by D. B. Dow- 



