CAMBRIAN BRACHIOPODA WALCOTT 85 



Observations. — The material representing this species was col- 

 lected by M. Schmalensee in the shaly beds of the Ceratopyge zone 

 of Oeland. The convexity, position of the apex, and clearness 

 of the false area depend upon the degree of compression and dis- 

 tortion to which the shells have been subjected. I have described 

 what appears to be the uninjured shell. 



The subcentral position of the apex seems to distinguish this spe- 

 cies. It is associated with Obolus (Broggeria) salteri (Holl) [1865, 

 p. 102] and LinguleUa lepis Salter [1866&, p. 334]- 



Formation and Locality. — Upper Cambrian: Ceratopyge slate 

 at Borgholm, Oeland Island, Sweden. 



ACROTHELE LEVISENSIS, new species 



Plate 8, Figure 13 



Outline transversely broad ovate, ventral valve moderately convex 

 at the apex, which is at about the posterior fifth of the length of the 

 valve ; pedicle aperture small and situated on the slope back of and 

 near the apex. Dorsal valve depressed convex, with a very gentle 

 slope from the umbo to the front margin and a greater slope to the 

 marginal beak. 



Surface marked by fine concentric lines and striae that cross the 

 space back of the apex without apparent interruption. A com- 

 pressed ventral valve 8 mm. in length has a width of 10 mm. A 

 dorsal valve has a length of 7 mm. ; width, 8 mm. 



The cast of the interior of a compressed dorsal valve shows a 

 median ridge that expands near the center of the valve, and a main 

 vascular sinus on each side that has the same general course as in 

 Acrothele coriacea Linnarsson [1876, p. 21]. 



Observations. — In general form this species is much like Acro- 

 thele coriacea and related species. It differs from them in having 

 a smooth surface except for the concentric lines and striae. 



The four specimens representing this species were attached to a 

 block in the collections of the Geological Survey of Canada, with 

 specimens of Elkaiiia desiderata (Billings) [1862, p. 69]. 



Formation and Locality. — Lower Ordovician : Levis shales, 

 Point Levis, Province of Ouebec, Canada. 



