528 CAMBRIAN BRACHIOPODA. 



LiNGULELLA PUNCTATA (Walcott). 

 Plate XX, figures 6, 6a. 



Lingulaf manticula Walcott [not White], 1884, Mon. U. S. Geol. Survey, vol. 8, pp. j.rf-X4, PL IX, fig. 3, and PI. 

 XI, fig. 2. (Discussed. The specimens represented by PI. IX, fig. 3, and PL XI, fig. 2, are redrawn in this 

 monograph, PI. XX, figs. 6 and 6a, respectively.) 

 Obolus (Lingulella) punctatus Walcott, 1898, Proc. U. S. Nat. Mus., vol. 21, pp. 412-413. (Described as below as a 

 new species.) 



General form ovate, with the ventral valve subacuminate. Valves moderately convex, 

 with the dorsal valve having a slightly depressed median sinus that extends from near the 

 umbo to the anterior margin. Surface of shell marked by lines and striae of growth, and very 

 fine, slightly undulating stride; also a few faintly indicated radiating strise; when the outer 

 layer is exfohated the outer surface of the inner layer is seen to be marked by numerous and 

 very fine radiating striae, in addition to the concentric fines of growth; the interior of the 

 shell, as shown by the casts, was strongly pitted or punctate, the punctae being arranged in 

 concentric lines following the lines of growth. The shell is relatively thin and formed of a 

 thin outer layer and one or more thin inner layers or lamellae. 



The type specimen of the ventral valve has a length of 9 mm., width 6.5 mm. An asso- 

 ciated dorsal valve has a length of 7 mm., width 5.5 mm. 



The only interior that shows anything more than the punctate surface is that of the dorsal 

 valve. In this the area is partly shown; it is relatively short and marked by fine striae par- 

 allel to its base, and two imperfectly developed flexure lines. The cast of a narrow median 

 septum is weU shown, and on each side of it the naiddle lateral muscle scars. The path of 

 advance of the central muscle scars is quite plain, also one of the scars. The only trace of 

 the vascular system is a portion of a main vascular sinus. 



This form owes its specific name to the concentrically punctate interior of the shell. 

 Formation and locality. — Upper Cambrian: (3f) Limestone at summit of canyon, 10 miles (16.1 km.) south 

 of Egan Canyon, east side of Egan Range, White Pine County; (8o) 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, White Pine County; (61) 

 limestone in the Dunderberg shale [Walcott, 19081, p. 184], a little south of the Hamburg mine, Eureka district 

 [Hague, 1892, Atlas], Eureka County; and (62) limestone in the Dunderberg shale [Walcott, 19081, p. 184], in canyon 

 immediately north of Adams Hill, Eureka district [Hague, 1892, Atlas], Eiu:eka County; all in Nevada. 



Middle Cambrian: (7i) Limestone just west of the summit on the road east of Schellbourne, Schell Creek Range, 

 White Pine County, Nevada. 



(54) Eldorado limestone [Walcott, 19081, p. 184], on east slope of Prospect Mountain, in New York Canyon; 

 (57) shaly limestone in the Eldorado limestone [Walcott, 1908f, p. 184], at the 700-foot (213.4 m.) level in the Rich- 

 mond mine, Ruby Hill [Hague, 1892, p. 43, and PL I, opposite p. 116]; and (58) shaly limestone in upper beds of 

 Secret Canyon shale, east side of Neio York and Secret canyons; all in the Eureka district [Hague, 1892, Atlas], Eureka 

 County, Nevada. 



Lingulella quadrilateralis (Walcott). 



Plate XXXIX, figures 6, 6a. 



Obolus (Lingulella) quadrilateralis Walcott, 1905, Proc. U. S. Nat. M-iz., vol. 28, p. 331. (Described and discussed 



as below as a new species.) 



General form rounded, quadrilateral; valves moderately convex. Surface marked by con- 

 centric fines and ridges of growth with fuie striae between. The surface of the inner layers 

 of the shell is shiny and marked by fine radiating striae in addition to the concentric lines. 

 The shell is rather thin; it is built up of several layers. 



Observations.— This species differs from other described species by its subquadrilateral 

 outfine. In this respect it may be compared with Obolus ( Westonia) cliuarensis (Walcott) (PI. 

 XXV), from which it differs in having a thinner shell and different surface markings. 



Formation and locality. — Middle Cambrian: (91) Conamuga {"Coosa") shale, at Cedar Bluff, Cherokee County; 

 and (56q) limestone at the very top of the Conasauga limestone, in quarry at Ketona, about 5 miles (8 km.) northeast 

 of Birmingham, Jefferson County; both in Alabama. 



(140a) Shales 200 yards (182.9 m.) east of Thomas Mills, 5 miles (8 km.) north of Cave Spring, Floyd County, 

 Georgia. 



