NO. 12%. CAMBRIAN BRACHIOPODA—WALCOTT. 603 



rather strong median ridge; they are elongate oval in outline, the 

 major axis inclining posteriorly- toward the median ridge. What 

 may be the impression of an antero-lateral scar occurs on the median 

 ridge a little in advance of the central scars. 



(Jh!<ervationii. — I collected a large number of this little shell in a 

 laj-er of gray limestone about 100 feet above the quartzitic sandstone 

 at the base of the Cambrian in the Black Hills. The associated tri- 

 lobites and brachiopods belong to the Middle Cambrian fauna of the 

 Upper ]Missi8sippi Valley and eastern Rock}- Mountain region. This 

 species differs from L. viinuta in the greater convexity of the pedicle 

 valve and the median ridge of the dorsal valve. The specific name is 

 given in recognition of the paleontologic work of Dr. George H. 

 (iirty. 



]Mr. E. O. Ulrich found this species in 1901 in great abundance in 

 gray limestones interbedded in the lower portion of the Middle Cam- 

 brian section of the Wichita jMountains. and Mr. R. Greger collected it 

 in the ^liddle Cambrian limestones near Potosi, Missouri. 



Fni'iiiiitinn andlocal'dy. — Middle Cambrian limestone in north sub- 

 urb of Deadwood, Black Hills, South Dakota. Also at the same rela- 

 tive horizon in Oklahoma Territory in calcareous layers of the Regan 

 greensand; one localit}^ is 15 miles northwest of Fort Sill, one-half 

 mile east of Canyon Creek, Wichita Mountains, and another is about 

 4 miles east of Canvon Creek in the southwest quarter section 17, T. 

 tl:N.,R. 12W. 



LINNARSSONELLA MINUTA Hall and Whitfield (sp.). 



Lingulepis {:') minuta Hall and Whitfield, Geol. Expl. Fortieth Parallel, IV, 



1877, p. 206, pi. I, figs. 3 and 4. 

 Lingulepis {F) mimita Walcott, Mong. U. S. Geol. Sur., VIII, 1884, p. IS 

 Lingulella miniita Schuchert, Bull. U. S. Geol. Sur., No. 87, 1897, p. 257. 



Shell small; general form broad ovate, with the pedicle valve 

 slightly subacuminate. The convexity of the two valves is nearly the 

 same and in each the minute beak is at the posterior margin. The 

 false area of the pedicle valve is small and divided midwaj' by a faint, 

 narrow, pseudodeltidium; it is on the plane of the margin of the 

 valve. Foraminal opening minute, elongate, and situated on the slope 

 just in front of the beak. Brachial valve a trifle less convex than the 

 pedicle. 



The outer surface of the shell is marked by fine concentric stria3 

 and lines of growth and the inner lamellae and inner surface by fine 

 radiating strife. The shell is formed of several thin layers or lamellae, 

 those of the anterior and lateral portions being more or less oblique 

 to the outer surface layer; the shell is also thickened in the visceral 

 region b}' irregular additions on the inside. The average length of 

 the pedicle valve is 2 to 2.5 millimeters; the dorsal is a little shorter. 



