534 CAMBRIAN BRACHIOPODA. 



(97s) "St. Croix sandstone" at Franconia, CMsago County; and (97) "St. Croix sandstone" at Reads Landing, foot of 

 Lake Pepin, Wabasha County; all in Minnesota. 



Middle Cambrian: (7j) Limestones at the north end of the Quinn Canyon Range, 1 mile (1.6 km.) northwest of 

 the Italian Ranch foothills, Nye County, Nevada. 



(360d) Siliceous limestones near Pike View, north of Colorado Springs, El Paso County, Colorado. 



(355a) Shales in Bear Gulch Valley; (88a) limestone about 100 feet {S0.5 ?)i.) aiove the quartzitic sandstone at the 

 hose of the Cambrian in the northern suburbs of Deadwood; (165) limestone on the east side of the valley, in railroad cut 

 about. 1 mile (1.6 km.) below the main part of Deadwood; and (17j) limestone in the east end of the town of Galena; 

 all in the Black Hills, South Dakota. 



(lie) Thin-bedded limestones south-southwest of Potosi, Washington County, Missouri. 



(10a) Sandy layers of the Rome formation, in western railroad cut through Shocks Gap, and (106) shales of the 

 Rome formation, on the roadside at the eastern base of Shooks Gap; both in Bays Mountains, 10 miles (16.1 km.) south- 

 east of Knoxville [Keith, 1895, areal geology sheet], Knox County, Tennessee. 



(9a) Limestone on the south shore of the Holston River at Melinda Ferry, 5 miles (8 km.) southwest of Rogers- 

 ville [Keith, 1896a, areal geology sheet], Hawkins County, Tennessee. 



(14a) Sandstone of the Rome formation along First Creek Gap, 4 miles (6.4 km.) north-northeast of Knoxville 

 [Keith, 1905, areal geology sheet], and (374) in the suburbs of and 4 and 11 miles (6.4 and 17.7 km.) north-northeast 

 of Knoxville; both in Knox County, Tennessee. 



(138) Shale in the street northeast of Printuf House, Gadsden, Etowah County, and (145) shale in bluff on 

 Coosa River east of Turkeytown, 8 miles (12.8 km.) northeast of Gadsden, Etowah County; both in Alabama. 



(362a) Sandy shale a short distance west of Cave Spring; (138a) shales in the Rome formation west of the ceme- 

 tery west of Rome; and (140c) shales at edge of hill on the road leading west of Cave Spring; all in Floyd County, 

 Georgia. 



Specimens that are somewhat doubtfully referred to this species occur at the following 

 localities : 



Middle Cambrian : (14t) Limestone lying on slope between the Cambrian quartzite and the massive blue lime- 

 stone 100 feet (30.5 m.) above. Mount Nebo Canyon, 3 miles (4.8 km.) southeast of Mona, Juab County, Utah. 



(92x) Conasauga ("Coosa") shale, at Yanceys Bend, Coosa River; and (90) Conasauga ("Coosa") shale on 

 Edwards's farm, near Craigs Mountain; both southeast of Center, Cherokee County, Alabama. 



U'- 



LiNGULELLA? SIMPLEX (Barraude). 

 Plate XXXII, figures 4, 4a-b. 



Lingula simplex Barrande, 1879, Systeme silurien du centre de la Boheme, vol. 5, pt. 1, PI. CIV, figs, vi: 1-4. (Not 

 described, but figured as a new species. Figs. lA, 4A, and 4B are reproduced in this monograph, PI. XXXII, 

 figs. 4, 4a-b, respectively.) 



This species, like Lingulella? insons (Barrande), is one of the forms that, with the present 

 evidence, is probably to be referred to Lingulella. All that is known to me of the species is shown 

 in the figures copied from Barrande. 



Formation and locality. — Lower Ordovician : (303a) Etage D3 at Trubin ; and (303p) Etage ds in the environ- 

 ofBeraun; both [Barrande, 1879b, PI. CIV] in Bohemia, Austria-Hungary. 



Lingulella tarpa (Walcott). 



Plate XXIII, figures 2, 2a-c. 



Obolus (Lingulella) tarpa Walcott, 1898, Proc. U. S. Nat. Mus., vol. 21, pp. 417^18. (Described and discussed as 



below as a new species.) 



General form elongate ovate, with the ventral valve subacuminate, and the dorsal valve 

 ovate in outline. There is considerable range of variation in the outline of both valves, owing 

 in part, possibly, to distortion. The convexity of the two valves is fairly strong, as far as 

 can be determined from the somewhat compressed condition of the shells in the shale and 

 calcareous sandy shales. The largest ventral valve in the collection has a length of 14 mm. 

 The average length of the ventral valve is from 10 to 12 mm. One 11.5 mm. in length has a 

 width of 8 mm. 



None of the specimens of the collection show the outer surface, and only traces of con- 

 centric and radiating lines have been observed on the inner surface. The shell appears to be 

 moderately thick, and formed of numerous lamellge that were oblique to the outer layer in the 



