PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 835 
DACTYLOGONIA SCULPTURATA Cooper, new species 
Plate 218, F, figures 17-21; plate 219, D, figure 10 
Shell large for the genus, wider than long and with the hinge forming the 
widest part; sides slightly rounded and slightly oblique ; anterior margin broadly 
rounded. Surface marked by strong and fine costellae, the latter exquisitely can- 
cellated by fine concentric lines; 5 or 6 of the stronger costellae occupy 5 mm. 
at the front margin; 5 or 6 of the fine costellae fill the spaces between the strong 
costellae. 
Pedicle valve fairly evenly and moderately convex in lateral profile and with 
no pronounced place of geniculation; anterior profile broadly and moderately 
convex. Umbonal and median regions somewhat swollen; lateral slopes long and 
moderately steep. Interarea long. 
Brachial valve moderately and broadly concave with the maximum concavity 
in the median region ; umbo sulcate; lateral areas somewhat flattened. 
Measurements in mm.—Holotype, length 16.2, brachial length 14.1, midwidth 
21.8, hinge width 22.5, thickness 3.8, surface length 18.0. 
Types.—Holotype: 117598a; figured paratype: 117598b. 
Horizon and locality —Bromide formation (Mountain Lake member) in Okla- 
homa: On the McLish Ranch, sec. 24, T. 1 S., R. 7 E., Johnston County ; 2,300 
feet south and 2,000 feet west of the northeast corner sec. 36, T. 1 S., R. 7 E., 
Johnston County; Baptist grounds along Falls Creek, SWA4NW4SW3 sec. 33, 
T.1S., R. 2 E., Murray County. 
Discussion.—This species is characterized by large size and the regularity and 
beauty of its sculpture. Its larger size suggests comparison with D. obsoleta 
(Butts), but that species is more strongly convex and more strongly geniculated. 
DACTYLOGONIA STRASBURGENSIS, Cooper, new species 
Plate 186, E, figures 15-19 
Shell large for the genus, length and width nearly equal; sides rounded; an- 
terior margin strongly rounded; surface marked by fine, distant strong radii 
numbering about 4 in 5 mm. at the front margin. Spaces between strong costellae 
marked by 4 or 5 fine costellae which are cancellated by fine concentric lines. 
Pedicle valve with unevenly convex lateral profile, the posterior half some- 
what flattened but the anterior half moderately convex. Anterior profile mod- 
erately domed; umbo narrowly convex, the convexity forming a low and short 
fold that disappears posterior to the middle; flanks bounding fold flattened to 
gently concave. 
Brachial valve having a shallow concavity with the maximum depth just an- 
terior to the middle; visceral region gently concave to nearly flat. Interior with 
short and delicate cardinalia. 
Measurements in mm.— 
Brachial Hinge Thick- Surface 
Length length Midwidth width ness length 
EV GIOUV BO oo .n sit td cians 19.1 ‘q 21.2 21.2 ? 23.0 
Paratype (117600a). 24.7 ? 23.5 22.8 > 30.5 
x (117600b) . ? 17.1 24.0 ? 28.4 ? 19.5 
