NO. lO CAMHRIAN FOSSILS, 4TH CONTRIBUTION RESSER 1/ 



This species is much more curved than H. foerstci and besides 

 has coarser ribs. 



Lower Cambrian, \\'eymouth ; Sandy Cove, Cohasset, Massa- 

 chusetts. 



Holofypc. — Boston Soc. Nat. Hist. no. 11963. 



Helcionella levis (Walcott) 



Stenotheca f rngosa levis Walcott (part), loth Ann. Rep. U. S. Geol. Surv., 

 p. 617, pi. 74, fig. 5a, 1891. 



Walcott inchided two forms in his variety levis. The smoother 

 one is chosen to represent the s^^ecies and the other described as 

 H. tcrranovica. 



Lower Cambrian, Etcheminian ; (loc. 41) Manuels, Conception 

 Bay, Newfoundland. 



Holotypc.—U.S.'^M. no. 18313. 



Helcionella elevata (Cobbold) 



Sceiiella cicvata Cobbold, Quart. Journ. Geol. Soc. London, vol. 76, pt. 4, 

 p. 364, pi. 24, fig. 36, 1921. 



Cobbold pointed out that this species did not conform to the re- 

 quirements of ScencUa but because it lacked pronounced concentric 

 rugosities reference to Helcionella was more difficult. Now that wide 

 variation in this respect is known to exist in Helcionella, the shape 

 of H. elevata may be relied on and the species referred to Helcionella. 



Lower Cambrian, Olencllus limestone ; Comley, Shropshire, 

 England. 



Holotype. — Geol. Surv. no. RR1211. 



Helcionella wheeleri (Walcott) 



Stenotheca n'hcclcri Walcott, Canadian Alpine Journ., vol. i, no. 2, pi. i, 

 fig. 7, 1908. 



Middle Cambrian, Stephen; (loc. 14s) Mount Stephen, near Field, 

 British Columbia. 



Holotype.— U.S. 'n.U. no. 96480. 



Helcionella belliana (Walcott) 



Platyccras (f) belliaiius Walcott, Canadian Alpine Journ., vol. i, no. 2, 

 pi. I, fig. 13, 1908. 



Occurrence same as preceding. 

 Holotype.— U.S.N. M. no. 96481. 



Helcionella romingeri (Walcott) 



Platyceras romingeri Walcott, Proc. U. S. Nat. Mus., vol. 11, p. 442, 1888; 

 Canadian Alpine Journ., vol. i, no. 2, pi. i, fig. 14, 1908. 



