714 CAMBEIAN BRACHIOPODA. 



Observations. — Through the courtesy and permission of Dr. Fr. Schmidt, Dr. Fr. von Huene 

 kindly sent me the types of this species, which he had been studying. One of them preserves 

 the outer shell at the apex. It shows a minute foraminal aperture on the back side of the apex 

 and a strong median groove on the false area. The outhnes of the pedicle valve vary from 

 the somewhat diagrammatic drawings of Kutorga [1848, PI. VII, figs. 7a-c], and there is 

 some variation among the five specimens representing the types. The characters of the shell 

 are shown by the figures on Plate LXXIII. 



Formation AND locality. — Ordovician. : (336) Echinosphxrites limestone, horizon Cla [Fr. Schmidt, personal 

 communication, 1906], Popowka, near St. Petersburg, Kussia. 



AOROTRETA ULRICHI Walcott. 



Plate LXXVIII, figure 3. 



Acrotreta ulricU Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 3, pp. 96-97, PL IX, fig. 3. (Described and 

 discussed as below as a new species. Fig. 3 is copied in this monograph, PI. LXXVIII, fig. 8.) 



This species is founded on a single specimen of a finely preserved ventral valve. The 

 outhne of the aperture is nearly circular, except for a short transverse portion beneath the 

 false area; surface moderately convex, with the apex curving and ending beyond the posterior 

 margin so that the minute foraminal aperture opens backward; a small false area is indicated 

 by a shght incurving at the cardinal angles; the area is without traces of a median furrow. 



Surface of shell marked by very fine, concentric striae and Hnes of growth. Length and 

 width of aperture 2 nun. ; convexity of ventral valve 1 mm. 



Observations. — This species is characterized by its curved umbo and apex, and overhang- 

 ing false area. It most nearly resembles A. curvata Walcott, from which it differs in being 

 less convex, and in the form of its umbo and curved apex. 



The specific name was given in honor of Mr. E. O. Ulrich. 



Formation and locality. — Upper Cambrian: (12p) About 225 feet (69 m.) above the igneous rocks, in the 

 limestones of the Reagan sandstone, at the northwestern extremity of the Arbuckle Mountains, about 4 miles (6.4 

 km.) east of Homer, Carter County, Oklahoma. 



/ ACEOTRETA UPLANDICA WimaU. 



/ 



Plate LXX, figures 3, 3a-c. 



Acrotreta uplandica Wiman, 1902, Bull. Geol. Inst. Univ. Upsala, vol. 6, pt. 1, No. 11, p. 54, PL II, figs. 15-18. (De- 

 scribed in German as a new species. The specimens represented by figs. 15-18 are redrawn in this monograph, 

 PL LXX, figs. 3, 3a-c, respectively.) 



Acrotreta uplandensis (Wiman), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28-, p. 302. (Characterized as below.) 



This species recalls at once Acrotreta idahoensis sulcata Walcott. It differs from it in 

 having a broader false area. The surface is marked by fine, threadhke striae that cross the 

 false area and false pedicle groove. 



Formation and locality. — Middle? Cambrian: (311b) Drift bowlder of gray bituminous sandstone, No. 2 [Wiman, 

 1902, p. 57], on Biludden, about 20 miles {S2.2 hm.) east of Gefle, Province of Oefieborg; and (Slip) drift bowlder of 

 glauconitic sandstone. No. 1 [Wiman, 1902, p. 57], at Hoganas, parish of Borstil, east of Osthammar, Province 

 of Stockholm; both in Sweden. 



Acrotreta uplandica limoensis (Wiman). 

 Plate LXX, figures 4, 4a-c. 



Acrotreta limomds Wiman, 1902, Bull. Geol. Inst. Univ. Upsala, vol. 6, pt. 1, No. 11, p. 54, PI. II, figs. 19-22. (Char- 

 acterized in German as a new species. The specimens represented by figs. 19-22 are redrawn in this mono- 

 graph, PL LXX, figs. 4, 4a-c, respectively.) 



Acrotreta uplandica limonensis (Wiman), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 303. (Characterized as 

 on p. 715.) 



