488 CAMBRIAN BRACHIOPODA. 



(2.4 km.) north of Boisdale; (101) shale on east bank of Barachois River, 6 miles (9.6 km.) from Little Bras d'Or Lake; 

 (3g[) shale in Barachois Glen, 4 miles (6.4 km.) south of Little Bras d'Or Lake; (3p and 372b) shale in ravine 0.5 mile 

 (0.8 km.) north of McMullins, on the crossroad to Boisdale; (16o) shales on McMullins Brook, in the east Boisdale 

 district; (3o and 372c) shale in ravine east of the railroad, just south of Barachois; and (372d) shale on McAdam 

 shore on East Bay, east of Bras d'Or Lake; all in eastern Cape Breton, Nova Scotia. 



Middle Cambrian: (3i) Compact, fine-grained, thin-bedded, gray sandstone of the Paradoxides zone, on McLean 

 Brook, 1 mile (1.6 km.) east of McCodrum Brook and 1.5 miles (2.4 km.) west of Marion Bridge, eastern Cape 

 Breton, Nova Scotia. 



A specimen from the following locality is provisionally referred to LinguleUa condnna: 



tTpper? Cambrian: (310h) Shale collected somewhere (probably Fogelsang), in the old Province of Skane, now 

 the Provinces of Malmohus and Christianstad, Sweden. 



LiNGIILELLA CUNEOLA (Wllitfield). 



Plate XXVII, figm-es 7, 7a-b. 



Lingulepis cuneolus Whitfield, 1877, U. S. Geog. and Geol. Survey Rocky Mtn. Region, Rept. Geology Black Hills 

 of Dakota; Prelim. Rept., pp. 8-9. (Described and discussed as below as a new species.) 



Lingulepis citncoZus Whitfield, 1880, U. S. Geog. and Geol. Survey Rocky Mtn. Region, Rept. Geology and Resources 

 Black Hills of Dakota, by Newton and Jenney, p. 336, PI. II, figs. 5 and 6. (Description copied from preceding 

 reference. The specimen represented by fig. 6 is redrawn in this monograph, PL XXVII, fig. 7.) 



Obolus {Lingulelln) cuneolus (Whitfield), Walcott, 1899, Mon. U. S. Geol. Survey, vol. 82, pt. 2, p. 443. (Merely 

 changes generic reference.) 



The original description by Whitfield follows : 



Shells small, rather below the medium size, triangularly ovate in outline or sometimes subcuneate; ventral valve 

 triangularly ovate, with a sharp somewhat pointed beak, the width and length about as three and four, and the point of 

 gi'eatest width near the lower thu-d of the length of the valve; cardinal slopes abrupt, scarcely convex; basal line 

 roimded at the sides, but nearly straight in the middle; surface of the valve strongly convex, becoming almost sub- 

 angular in the upper part; dorsal valve much shorter proportionately than the ventral, the length but little exceeding 

 the width; side and base more rounded and the beak truncate; sm-face distinctly convex. 



Surface of the shell apparently smooth, but usually exfoliated, in which condition a few fine radiating lines are 

 visible. 



This shell differs from L. pinnaformis Owen in size and in the more distinctly cuneate form of the ventral valve. 

 At first sight it might be taken for the young of that species, but a little critical examination soon reveals marked dis- 

 tinctions in the truncation of the front margin, and especially in the form of the cardinal slopes, which are rounded 

 and never concave, as in almost all ventral valves of that species. In consequence of this latter featiu-e the beak does 

 not appear so attenuated as in that one, although proportionately quite as long. In the general surface characters and 

 form of the valves it corresponds with the genus Lingulepis, although we have not been able to distinguish the muscular 

 impressions. 



Were it not for the difference in the size of the shells we should be inclined to think this might be the species 

 figured by Messrs. Meek and Hayden [1865, p. 3, PI. I, figs, la-b] as Lingulepis dakotensis; but as their figures appear 

 to be of the natural size, we should suppose it to be very distinct, as all the specimens of our shell noticed have been 

 small, none exceeding one-fourth of an inch in length. 



Observations. — This species does not appear to be correctly referred to Lingulepis. In 

 outline it resembles some of the cuneate forms of LinguleUa, and in its thick laminated shell it 

 approaches Lm^uZeZZajj/iaon (Walcott) (PI. XXVI). Like that species, it has a thick outer layer 

 and strong, radially striated inner layers, and numerous lamellee slightly oblique to the outer 

 layer over the anterior portions of the shell, especially about the anterior and lateral margins. 

 Most of the specimens are in the form of partial casts, only a portion of the outer shell adhering 

 to the cast. 



The form of the ventral valve approaches that of some of the broader shells of LinguleUa 

 perattenuata (Whitfield) (PI. XXI). It diifers, however, in being more cuneate. Except for 

 the somewhat straighter slope of the sides toward the beak it might be identified with LinguleUa 

 acutangula (Roemer) (PL XVII). Although fairly large collections were made from the Cam- 

 brian formations in the Black Hills during the field season of 1897, no specimens were found 

 that could be definitely identified as belonging to this species, the only material available for 

 study being that in the original collections of W. P. Jenney. 



Formation and locality.- — Middle Cambrian: (355) Sandstones in Red Canyon Creek, southwest side of the 

 Black Hills, South Dakota. 



