678 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
ditch on east side of road 2,300 feet south and 2,000 feet west of the northeast 
corner of sec. 36, T. 1 S., R. 7 E., 1 mile west of Dolese Brothers Crusher, Bro- 
mide, Johnston County; zone 36, on Oklahoma Highway 99, SW4NW4SW4 
sec. 12, T. 1 N., R. 6 E., Pontotoc County; Mimella zone, Baptist grounds at 
Falls Creek, SWANW4SW3 sec. 33, T. 1 S., R. 2 E., Murray County; bed 2, 
west of Nebo store, sec. 22, T. 2 S., R. 3 E., Murray County; road cut on east 
side of section line road, 1,300 feet south of the northwest corner of sec. 23, 
T.1S., R. 3 E., opposite road to abandoned town of Gilsonite, Murray County ; 
50 to 75 feet below ford of Hickory Creek, 2 miles west of Overbrook, Carter 
County ; 2 miles northeast of Springer, McLish Ranch, sec. 24, T. 1 S., R.7 E., 
Johnston County. 
Discussion.—This species is characterized by its elongate form and the elonga- 
tion of the beak which is not strongly incurved. In this respect it resembles 
P. superba, but that species is larger, wider, and more deeply sulcate than 
P. elongata. Confusion with P. loeblichi is not likely to occur because that species 
is wider and with a much less elongated beak. 
Protozyga elongata is a variable species as are all members of this genus. The 
variation takes form in more convex or somewhat wider individuals with a less 
elongated beak. If found by themselves, some of these might be assigned to 
other species. 
PROTOZYGA EXIGUA (Hall) 
Plate 119, D, figures 9-14; plate 140, F, figures 38-42; plate 142, G, figures 29-33 
Atrypa exigua (HALL), Pal. New York, vol. 1, p. 141, pl. 33, fig. 6, 1847—-EmmMons, Amer. 
geology, vol. 1, pt. 2, p. 190, pl. 10, fig. 6, 1855.—LresLey, Pennsylvania Geol. Surv., 
Rep. P. 4, p. 55, 1880. 
Genus ? exigua HALL, 12th Rep. New York State Cab. Nat. Hist., p. 66, 1850. 
Protozyga exigua (Hall) Hai and CLarKe, Pal. New York, vol. 8, pt. 2, p. 149, figs. 137, 
138 (not pl. 54, figs. 47, 48), 1893. 
Zygospira exigua (Hall) ScHucuert, U. S. Geol. Surv. Bull. 87, p. 463, 1897. 
Large for the genus, pentagonal in outline; strongly inequivalve; postero- 
lateral margins nearly straight, forming an apical angle of about 100°. Greatest 
width at or near the middle. Sides narrowly rounded. Anterior margin broadly 
rounded. Anterior commissure broadly sulcate. Surface paucicostate, about 5 
obscure costae on the flanks, fold and sulcus variably costate. 
Pedicle valve strongly convex in lateral profile and with the maximum con- 
vexity at about the middle; anterior profile narrowly convex in the middle and 
with depressed and concave sides. Umbonal region narrowly convex, continued 
anteriorly as a strong, steep-sided fold which is flattened on top and often with a 
slight depression. Fold with 2 or 3 obscure costae. Flanks concave but with 
lateral areas deflected slightly in the direction of the pedicle valve. 
Brachial valve moderately convex in lateral profile; maximum convexity at 
about the middle; anterior profile gently and broadly convex but with a narrow 
and shallow median depression. Umbo sulcate; sulcus shallow throughout its 
length from umbo to anterior margin; fold in sulcus originating anterior to 
