442 NEW GENERA AND SPECIES OF CAMBRIAN FOSSILS. 



Formation and locality: Middle Cambrian, 2,000 feet above the Ole- 

 nellus horizon, Mt. Stephen section, British Columbia. Collection of 

 Dr. Karl Koininger. 



Linnarssonia sagittalis Suiter (sp.). 



A beautifully preserved interior of the dorsal valve of this species 

 came from the same locality as the preceding species. 



Orthisina alberta n. sp. 



Shell transversely suboval, front broadly rounded; the straight 

 hinge line is shorter than the full breadth of the valve; area of the 

 central valve high, bent backward from the hinge line, divided by a 

 large foramen that is covered by a convex deltidium. The area of the 

 dorsal valve slopes back at about a right angle to the valve. The 

 broad, short foramen appears to have been covered by a low deltidium. 



Surface marked by radiating costaj, five in a distance of 3 ,UI " on the 

 frontal margin. 



This species recalls Orthis lindstromi Linnarsson, from the Paradoxi- 

 des zone of Sweden. 



Formation and locality : Middle Cambrian, 2,000 feet above the Ole- 

 nellus zone, Mt. Stephen section, British Columbia. Collection of Dr. 

 Karl Romiuger. 



Platyceras romingeri n. sp. 



Shell small, apex incurved, body whorl expanding rapidly on the outer 

 half of the volution; dorsum broad, subaugular (?) on the right side: 

 left side concealed in the matrix. The body volution is marked by con- 

 centric undulations, aperture and peristome broken. Surface marked 

 by concentric stria 1 of growth. A second specimen, that is pressed flat 

 in the shale, shows the outer volution quite regularly rounded, the 

 aperture subcircular and the peristome smooth. 



Formation and locality: Middle Cambrian, 2,000 feet above the Ole- 

 nellus zone, Mt. Stephen section, British Columbia. Collection of Dr. 

 Karl Bomiuger. 



The Genus OLENOIDES Meek. 



It is unfortunate that genera occurring in the three divisions of the 

 Cambrian system have names so liable to be confused; viz, Ulenus, 

 Olenellus, and Olenoides. Olenus and Olenellus are respectively typi- 

 cal genera of the Upper and Lower Cambrian, and Olenoides attains its 

 greatest development in the Middle Cambrian, in areas where the 

 characteristic Atlantic province genus Paradoxides is absent. All 

 three of the names have been used in published memoirs, and students 

 will be obliged to distinguish them despite of their similarity. 



The genus Olenoides was proposed by Mr. B. F. Meek 1 for a species 

 which he provisionally referred to the genus Paradoxides— P.(t)nevaden- 

 sis. In the description of the Middle Cambrian fauna 2 the type specimen 



'Geol. Expl. Fortieth Par., vol. iv, pt. 1, p. 25. 

 2 Bull. U. S. Geol. Survey, No. 30, p. 180, 1886. 



