CAMBRIAN BRA CHIOPODA— WALCOTT. 611 



defined pedicle furrow. The flexure line is just perceptible about half 

 the distance out from the pedicle furrow to the lateral niarg-in. The 

 area extends well forward on the cardinal slopes, and is marked liy 

 strong stricT? of growth parallel to its base. The area of the dorsal 

 valve is shorter than that of the ventral. It is marked by fine lines of 

 growth and clearly marked flexure lines that extend from the apex 

 forward on a line with the main vascular sinuses. 



The cast of the interior of the ventral valves shows a general outline 

 of the visceral cavity and the main vascular sinuses. Only the base of 

 the main vascular sinus has been seen in the dorsal valve. 



Observatlons.—This very pretty little species occurs in association 

 with Pamdoxides. In my first study of the brachiopods collected by 

 S. Ward Loper from Cape Breton I confused it with the young of 

 0. (Z.) gregira. By means of a larger collection made by him in 1901 

 I have been able to separate it from the young of the associated O. 

 {Lin guleph) paradox idea ^ and from the somewhat similar species that 

 occur at a lower horizon, 0. (Z.) atavm and O. (Z.) colUcia. It differs 

 from both the latter species in having a more elongate oval outline. 



FoTiimt'ujn ayid locality. — Middle Cambrian; compact, fine-grained, 

 thin-bedded, grayish sandstone, McLean's Brook, 1^ miles west of 

 Marian Bridge, Cape Breton, Nova Scotia. 



OBOLUS (WESTONIA) FINLANDENSIS, new species. 



General form elongate ovate, with the ventral valve subacuminate 

 and the dorsal valve ovate in outline. Convexity of the two valves 

 moderate. A ventral valve 11 mm. in length has a convexity of about 

 1.25 mm., and a dorsal valve 8 mm. in length a convexity of 1 mm. 

 above the plane of the margin. 



The outer surface of the shell is marked by concentric lines of 

 growth, with very fine interstitial stria^. The latter are crossed by 

 fine radiating strite that are interruDted more or less by the concen- 

 tric lines of growth. In addition to the concentric radiating strife 

 there is a series of imbricating lines that are slightly oblique to the 

 longitudinal axis of the shell. These lines terminate at right angles to 

 the margins, curving inward and backward apparently to the opposite 

 side. This type of ornamentation is much like that of several species 

 of WesUmia, except that it is somewhat more complicated. 



The cast of the interior of the shell shows the interior surface to 

 have been marked by scattered puncta? that had a tendency to gather 

 concentrically on the lines of growth. A few rather strong radiating 

 striae also occur outside of the visceral area. 



The shell is rather thick. It is formed of a thin outer layer and 

 several inner layers or lamella? that are more or less oblique to the 

 outer surface and marked near the front margin by fine radiating 

 striffi. The largest specimen has a length of 11 mm. with a width of 

 7 mm. The dorsal valve of the same width has a length of 8 mm. 



