550 CAMBRIAN BRACHIOPODA. 



(355) Sandstones on Red Canyon Creek, southwest side of Black Hills; (355d) sandstone in the Black Hills; 

 (164) sandstone in the Deadwood formation p the cliffs on the east side of the valley near Deadwood, Black Hills; 

 (167) sandstone beneath limestone and resting on the pre-Cambrian in a bluff 9 miles (14.4 km.) west of Custer, 

 Black Hills; and (355b) sandstone in the Deadwood formation on Castle Creek, west side of Black Hills; all in South 

 Dakota. 



(171 and 171a) Sandstone in Big Goose Creek Canyon, Bighorn Mountains, west of Sheridan, Sheridan County; 

 (302m) middle of shale above lower sandstone on Billy Creek, in the Bighorn Mountains, Sheridan County; and (340c) 

 dark-red sandstone near the base of the Cambrian at Rawlins, Carbon County; all in Wyoming. 



LiNGULELLA (LlNGXJLEPIs) ACTJMINATA MEEKI (Walcott). 

 Plate XLI, figures 2, 2a. 



Lingulepis meehi Walcott, 1897, Am. Jour. Sci., 4th ser., vol. 3, p. 405. (Described and discussed as below as a new 



species.) 

 Obolus (Lingulepis) acuminatus meehi Walcott, 1899, Mon. U. S. Geol. Survey, vol. 32, pt. 2, p. 444, PL LX, figs. 



1 and la. (Text copied from preceding reference. The specimens represented by figs. 1 and la are redrawn 



in this monograph, PI. XLI, figs. 2 and 2a, respectively.) 

 Obolus (Lingulepis) acuminata weehsi Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 333. (Merely used for Obolus 



(Lingulepis) acuminata meehi by mistake in discussion of " Obolus (Lingulepis) eras.") 



Shell small, attenuate, marked by rather strong concentric lines and striae of growth, 

 and interrupted, irregular, radiating striae. 



Ventral valve narrow, elongate, beak acuminate, rostral slopes long, nearly straight, 

 passing gradually into the curvature of the anterolateral margins, and posteriorly meeting 

 at a very acute angle; front strongly rounded. Length of valve, 8 mm.; width, 3.5 mm., the 

 widest portion being near the anterior extremity. Beak slightly upcurved, the longitudinal 

 median line straight or even slightly concave from the apex of the beak to the middle, where 

 it begins to slope gently to the frontal margui; transverse curvature very slight anteriorly, 

 more convex than the beak. 



Dorsal valve more convex than the ventral, linguliform ; beak depressed, bluntl.y rounded, 

 curving evenly and gradually to the semitruncate anterior margin. 



Observations. — The interior markings of this shell have not been ascertained, but the 

 external characters are such as to make a reference to the subgenus Lingulepis more than 

 probably correct. The flat, acute-acuminate ventral vah^e with its elevated or retrorse beak, 

 which is not covered by the smaller dorsal valve, is characteristic of Lingulepis. 



There is a form from. Texas, probably identical with Lingulella perattenuata (Whit^eld) 

 that might be mistaken for this variet}', but it is an undoubted Lingulella and does not show 

 the external characteristics of lAngulepis. A comparison of Lingulella (Lingulejns) acuminata 

 meelci with the young 'and narrow specimens of L. (L.) acuminata (Conrad) shows it to vary 

 from that species, the posterior rostral slopes of X. (L.) acuminata possessing a peculiar incurv- 

 ing which is not shown in L. (L.) acuminuta meeM. 



After the publication of "Lingulepis meelci'' [Walcott, 1897, p. 405] shells were collected 

 from the north end of the Teton Range, which showed that that form was very closely related 

 to L. (L.) acuminata. As all the Teton Range shells were quite small and the majority had 

 the characters of "Lingulepis meelci," the latter was reduced to a variety of L. (L.) acuminata 

 [Walcott, 1899, PL IjX, figs. 1 and la], and the Teton shells were included with those from the 

 Gallatin Range. 



The varietal name was given in honor of. Dr. F. B. Meek. 



Formation and locality. — Middle Cambrian : (302b) Limestones near Crowfoot Ridge, Gallatin quadrangle ( U. S. 

 Geol. Survey), Yellowstone National Parh; and (4e) limestones about 950 feet (289.6 m.) above the unconformable 

 base of the Cambrian in the divide at the head of Jackson Creek (locally known as Sheep Creek), a creek flowing into 

 Jackson Lake about 0.5 mile (0.8 km.) south of its northwest corner, Teton Mountains, Grand Teton quadrangle (U. S. 

 Geol. Survey), Uinta County; both in Wyoming. 



(4h) About 375 feet (114.3 m.) above the base of the Cambrian in limestone interbedded in the Flathead shales 

 of Peale [1893, p. 21], 1 mile (1.6 km.) north of the junction of East Gallatin and West Gallatin (Gallatin) rivers, 4 

 miles (6.4 km.) east-northeast of Logan, Thi-eeforks quadrangle (U. S. Geol. Survey), Gallatin County, Montana. 



