""BE ] CANADIAN PALAEOZOIC COEALS. 115 



gradually decreasing in size upward, their free edges bearing denticula- 

 tions that extend over their sides as obscure carinse ; the secondary septa 

 are similarly formed but are conspicuously smaller, and at times are 

 scarcely more than uniserial rows of tubercles. Septa in average sized in- 

 dividuals from about sixty to eighty in number, the primaries beneath 

 the floor of the cup passing to the centre, their inner ends being slightly 

 twisted and frequently united in twos and threes before reaching the 

 centre, the secondaries very small. Dissepiments comparatively large, 

 directed convexly upward and inward toward the centre in the inter- 

 septal spaces and forming with the septal ends the central structure 

 whose upper surface constitutes the convex floor of the cup. 



With this species is identified the small Streptelasma from the upper 

 and lower beds of the Hudson River formation at Stony Mountain, Man., 

 collected by R. W. Ells in 1875, and by T. 0. Weston in 1884. 



Localities. — Anticosti, Que., at 3 miles west of Jupiter River, at East 

 Point and at the " Jumpers," in divisions II., III., and IV. of the Anti- 

 costi group; collected by James Richardson in 1856. 



Streptelasma. latusculum, var. trilobatum, Whiteaves. 



Streptelasma rusticwm, var. trilobatum, Whiteaves. 1895. Palseoz. Foss., vol. III., pt. 



II., p. 113. 



This variety is represented by some well preserved specimens collected 

 by Mr. T. 0. Weston, at Stony Mountain, Manitoba, in 1884. 



The normal form from this locality is thought to more nearly resemble 

 Streptelasma latusculum than S. rusticum, and has been referred to the 

 former species (see p. 114), in consequence of which the trilobed variety 

 has been classed under the above name. 



Formation. — Hudson River. 



Streptelasma peolificum, Billings. (Sp.) 

 Plate VIII., figs. 1, la. 



^aphrentis proUfica, Billings. 1858. Rep. of Progress for 1857, Geol. Survey of Canada 



p. 176. 

 „ „ Billings. 1859. Canadian Journal, new series, vol. IV., p. 121, 



figs. 22, 23. 

 ? Zcuphrentis corticata, BiUings. 1874. Palffioz. Foss. vol. II., pt. I., p. 9, pi. I., figs. 4, 



4a, 4b. 

 Zaphrentis proUfica, Nicholson. 1874. Palseon. of Ont., p. 23, pi. III., figs. 2, 2a ; and 



1875,. Geol. Surv. of Ohio, vol. 11., p. 237. 



L-2J 



