48 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 78 



BEYRICHONA ALTA Wiman 



Plate 7, Figure 13 



Beyrichona alia Wiman, Bull. Geol. Inst. Upsala, vol. 6, pt. 1, 1902, p. 47, pi. 3, 

 fig. 53. 



The type and only specimen is an imperfect valve, but according 

 to the figure of it published by Wiman it clearly represents an elongate 

 species of Beyrichona. 



Occurrence. — Lower Cambrian, Olenellus bituminous sandstone: 

 Limon near Gefle, Sweden. 



BEYRICHONA? RUTELLUM (Matthew) 



Plate 1, Figure 32; Plate 3, Figure 21 



Escasona rutellum Matthew, Canadian Rec. Sci., vol. 8, 1902, p. 458, pi. 2, 

 figs. 5a-5c; Geol. Surv. Canada, Rept. Cambrian Rocks Cape Breton, 

 1903, p. 167, pi. 13, figs. 5a-5c. 



Depending solely upon the original type of this species, B. 

 rutellum appears to be a short hinged form in which the essential 

 features of Beyrichona are recognizable only in a subdued condition; 

 that is, they are somewhat obscurely developed. The hinge is con- 

 siderably shorter than the height, the dorsal depression is smaller 

 and less defined than usual, and the antero-dorsal node, as well as 

 the sulcus immediately behind it, less distinctly developed. Still, 

 all these features of Beyrichona are so clearly recognizable that 

 generic separation seems undesirable. On the other hand, it is not 

 to be denied that the surface pitting and general aspect of the valve 

 is not greatly different from species of Bradoria hke B. cambrica. 

 Possibly with more specimens (we have seen only Matthew's original) 

 it may be shown that the affinities of the species are really nearer 

 Bradoria than Beyrichona. In that case Esca.sona might stand, but 

 in no case should it include Beyrichona ovaia, which olso has an 

 unusuall}'^ short hinge. 



Occurrence. — Lower Cambrian (Etcheminian, division E3/): Gillis, 

 Indian Brook, Cape Breton, Nova Scotia. 



DOUBTFUL SPECIES 



ESCASONA INGENS Matthew 



Plate 1, Figure 31 



Escasona (?) ingens Matthew, Canadian Rec. Sci., vol. 8, 1902, p. 459, pi. 2, 

 figs. 7a-c; Geol. Surv. Canada, Rep. Cambrian Rocks Cape Breton, 1903, 

 p. 168, pi. 13, figs. 7a-c. 



The single specimen bearing this name, hence the type, is so in- 

 definitely preserved that it would be unsafe to venture an opinion. 



Occurrence. — Lower Cambrian (Coldbrookian) : Dugald Brook, 

 Nova Scotia. 



