110 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



ling and L. M. Lambe in 1890, at Dog Head, Dancing Point, Little 

 Tamarack and Selkirk islands, and on the main shore opposite the north 

 end of Selkirk Island and north of the Saskatchewan by D. B. Dowling 

 in 1891. Most of the specimens from these localities appear to widen 

 out much more rapidly, at a short distance from the pointed base, than 

 any of the eastern examples of S. corniculum do, but a single specimen 

 from Little Black Island approaches very near to that species. 



" A small specimen, which is probably also referable to S. robustum, 

 was collected at the junction of the Little and Great Churchill rivers by 

 Dr. R. Bell in 1889. 



" When fully grown this species can be readily distinguished from S. 

 corniculum by its very much larger size and more robust habit of growth." 

 (Whiteaves.) 



Formation. — Galena-Trenton. 



Streptelasma rusticum, Billings. (Sp.) 



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



Streptelasma corniculum, Milne-Edwards and Haime. 1851. Polyp. Foss. des Terr. 



Paleeoz., p. 398, pi. 7, figs. 4, 4a, 46. 

 Petraia rustica, Billings. 1858. Rep. of Progress for 1857, Geol. Survey of Canada, 



p. 168. 

 Zaphrcntis Canadensis, Billings. 1862. Palseoz. Foss. vol. I., p. 105, figs. 93 a — c. 

 Petraia Canadensis, Billings. 1863. Geology of Canada, p. 208, fig. 205. 

 Streptelasma corniculum, Nicholson. 1875. Palseon. of Ont., p. 26 ; and Geol. Surv. of 

 Ohio, vol. II., p. 218. 

 ii ii Rominger. 1876. Geol. Sur. Mich., Foss. Corals, p. 141 (pars), 



pi. LI., upper row, specimens from the Hudson River formation 

 only. 



Original description. — "Straight or slightly curved, covered with a 

 strong epitheca, which is more or less annulated with broad shallow 

 undulations ; radiating septa about one hundred or usually a little more ; 

 much confused in the centre, where they form a vesicular mass ; every 

 alternate septum much smaller than the others, only half the whole num- 

 ber reaching the centre. Length from two inches and a half to three 

 inches and a half. Diameter of cup one inch to one inch and a half ; 

 depth of cup half an inch or somewhat more. 



This species appears to be the same as that described by Edwards 

 and Haime under the name of Streptelasma corniculum. The true S. 

 corniculum of Mr. Hall is a very different species, being always shorter 

 nd much curved. 



