N0.1395. CAMBRIAN BRACHIOPODA—WALCOTT. 271 



The character of the costpe and general features of this shell, as far 

 as known, appear to class it with P. remniehd and allied forms. 



Formation and loeality. — Middle Cambrian. Sandstone and sandy 

 shales, McFees Point, near George River station, Cape Breton, Nova 

 Scotia. 



PLECTORTHIS SALTENSIS Kayser. 



Ortkis saltensis Kayser, Pal?eontographica, Primord, and Sil. Foss. Argentinischen. 

 Rep., 1876, p. 8, pi. i, fig. 16. 



Doctor Kayser\s description of the ligures lead me to refer this spe- 

 cies to the genus Plectortlih. The general form of the valves, the 

 casts of the interior of the ventral valve, with the strong umbonal cavity 

 and the radiating ribs, increasing in number by intercalation of new 

 ribs, appear to sustain the reference. 



Formation and locality. — Upper Cambrian. Sandstone of Salta and 

 Nevado de Castillo, and at Tilcuya, Argentine Repidjlic. 



Doctor Kayser also described and illustrated the dorsal valve of a 

 shell that he referred to Ortlds sp. It suggests Ort/ii.s {(/rusia) 

 lenticular Is. 



PLECTORTHIS TULLBERGI, new species. 



This shell occurs in the passage beds to th(? OrdoA'ician at the top of 

 the Ceratopyge zone. Its transverse outline and simple, strong ribs 

 serve to distinguish it from P. cliristianiw and P. daunus. 



The specific name is given in memory of Sven Axel Tullberg. 



Formation and locality. — Upper Cambrian. Ceratopyge zone, 

 Olands, Borgholm, Sweden. 



PLECTORTHIS WICHITAENSIS, new species. 



In general form and outline this shell is related to P. desmopleura 

 and P. remnicha. It is more convex and ditl'erences in the radial rib- 

 bing and striation separate it from the former species, and it occurs in 

 an older geological formation. Its convexity and surface characters 

 distinguish it from P. niimir/ui. 



A considerable number of relatively smooth shells occuis in the col- 

 lections that may be designated as a variety, })ut it is often difficult 

 to separate them from the more tinely ribbed specimens that arc 

 typical of the species. 



Formation, and locality. — Upper part of Middle Cambrian and )jasc 

 of Upper Cambrian. 



Middle Cambrian, Reagan formation. A little soutli of W. \ of sec. 

 2, T. 4 N., R. 13 W. One-quarter mile soutb of Canyon Creek Camp. 

 15 miles northwest of Fort Sill, Wichita Mountains. Also in same 

 area near middle of west half of sec. 13, T. 4: N., R. 13 W.; 2 miles 

 south and 1 mile east of (knyon C!reek Camp; also in SW. \ sec. 17,4 

 miles east of Canyon Creek Canip, 11 miles northwest of Fort Sill, 



