412 CAMBKIAN BRACHIOPODA. 



(80) Limestone on the slope of the ridge where the range swings around to the northwest, 2 miles (3.2 km.) north 

 of Aurum, Schell Creek Range, AATiite Pine County, Nevada. 



(96) Limestone near the ford on the Cedartown road, 1.5 miles (2.4 km.) south of Rome, Floyd County, Georgia. 



Kiddle Cambrian: (159) Limestones north of West Gallatin (Gallatin) River, Gallatin County, Montana. 



(302b) Limestones near Crowfoot Ridge, Gallatin quadrangle (U. S. Geol. Survey), Yellowstone National Park, 

 Wyoming. 



(34n) Shales about 100 feet (30.5 m.) above the Tintic quartzite [G. 0. Smith, 1900, p. 1] near the simimit of the 

 ridge between Mammoth and Eureka, Tintic special quadrangle (U. S. Geol. Survey), Juab County, Utah. 



(llo) About 2,750 feet (838.2 m.) above the Lower Cambrian and 1,650 feet (502.9 m.) below the Upper Cambrian, 

 at the base of the limestone forming la of the Marjum limestone [l\'alcott, IQOSf, p. 179], about 4 miles (6.4 km.) 

 southeast of Antelope Springs in the spur at the junction of the Deseret and Swasey Spring roads [Walcott, 1908f, 

 PL XIII], House Range, Millard County; (llx) about 2,200 feet (670.6 m.) above the Lower Cambrian and 2,200 feet 

 (670.6 m.) below the Upper Cambrian in the limestones forming Id of the Marjum limestone [Walcott, 19081, p. 180], 

 2.5 miles (4 km.) east of Antelope Springs, in ridge east of Wheeler Amphitheater [Walcott, 1908f, Pis. XIII and 

 XV], House Range, Millard County; all in Utah. 



(7i) Limestone just west of the summit on the road east of Schellbourne, Schell Creek Range, White Pine County; 

 and (7j) limestones at the north end of the Quinn Canyon Range, 1 mile (1.6 km.) northwest of Italian Ranch foothills, 

 Nye County; both in Nevada. 



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

 locality: 



Upper Cambrian: (8p) Limestone halfway up the canyon east of McGill's ranch, on the west side of the Schell 

 Creek Range, 14 miles (22.5 km.) northeast of Ely, ^Vhite Pine County, Nevada. 



Obolus schmalenseei (Walcott). 



Plate XXX, figures 19, 19a-e. 



Obolus {Lingulella) schmalensei Walcott, 1902, Proc. U. S. Nat. Mus., vol. 25, p. 605. (Characterized as below aa a 

 new species.) 



This is the European representative of the American Obolus rotundatus (Walcott) (PI. XX). 

 Its outline is slightly elongate to subcircular. Wlien the shell is exfoliated, the cast indicates 

 that it was strong over the visceral area and tliin toward the margins. The characteristic 

 features are well shown in the drawings. 



The specific name is given in honor of Mr. Schmalensee, who collected the material for me. 



Formation and locality. — Middle Cambrian: (8w) Limestones of Paradoxides forchhammcri zone, at Andrarum, 

 20 miles {32 km.) northwest of Simrishamn, Province of Christianstad, Sweden. 



(16h.) Limestones of the. Parado.vides forchhamineri zone, at Borregaard; and (16i) limestones of the Conocoryphe 

 exsulans zone, at Borregaard; both on Bornholin Island, Denmark. 



Obolus schmidti Mickwitz. 



Plate XV, figures lla-c. 



Obolus schmidti Mickwitz, 1896, M6m. Acad. imp. sci. St.-P^tersbourg, 8th ser., vol. 4, No. 2, pp. 152-154, PL II, 

 figs. 14a-c. (Described and discussed in German as a new species; see below for translation of the diagnosis. 

 Figs. 14a-c are copied in this monograph, PL XV, figs, lla-c, respectively.) 



The original description by Mickwitz follows: 



Shells large, moderately arched; outline broad, egg-shaped; posterior borders of shell convex, not winged; beak 

 of the large shell scarcely prolonged. Surface of shell faintly polished. Growth lafnellse marked by deep, regular, 

 roughly cut concentric furrows. Concentric striae fine, irregular, mingled. Radial stri^ perceptible as indistinct 

 traces. Area of large shell very small, peduncular groove pit-shaped. Thickening of posterior part of shell falling 

 away in two terraces to middle of shell. First terrace is steep at the broadest place of the heart-shaped groove, the 

 second flat in front of the point of the latter. Posterior part of the thickening in the form of two club-shaped swell- 

 ings, which, separated at their posterior thick parts by a deep furrow in the prolongation of the peduncular groove, 

 pass over with their anterior ends into the swellings of the principal vessel furrows. Splanchnocoele of the large shell 

 strikingly shortened. Secondary, inwardly diverging traces of the vessels rectilinear, not ramified. 



Ohservalions. — Mick^vitz states that, in addition to the concentric strise described and very 

 faint traces of radial strias, there are over the entire rather rough surface of the shell scattered, 

 irregular, flat grooves, whose radial position is unmistakable. He also calls attention to the 



