PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 719 
strongly swollen, with steep slopes in all directions; anterior slope the steepest. 
Pseudodeltidium narrow; interarea long, orthocline. Interior with short, flat 
teeth; callosities appearing on each side of teeth and extending parallel to hinge ; 
diductor scars long, extending to the middle and ending on high callosities ; pallial 
marks strongly developed. 
Brachial valve closely following the curvature of the pedicle valve, most con- 
cave in the median region; umbo concave, the concavity continued anteriorly as 
a shallow sulcus to a point anterior to the middle; interarea moderately long, 
hypercline. Interior with well-marked but low median septum in the young ; old 
adults with septum obscured by adventitious shell; adductor impressions small ; 
pallial trunks well developed ; ovarian impressions moderately large, marked by 
fine, wavy lines ; brachiophores small ; callosity parallel to edge of palintrope sepa- 
rated from hinge margin by groove. 
Measurements in mm.— 
Brachial Surface Hinge 
Length length length Midwidth width Thickness 
Hypotype (117421)..... 23.6 20.1 30.5 29.1 ? $3.0 7 4.6 
5 CIT7AZ2 ie .8 25.1 ? 35.0 37.6 ? ? 
ss (177418) 00.5 i 23.9 ? 37.9 ? ? 
Types.—Figured hypotypes: 117416, 117417, 117418, 117420a, 117421, 
117422, 117423b. 
Horizon and locality—Arline formation in Tennessee: 6 miles southeast of 
Knoxville; north side of old wagon road in glade, } mile southeast of Friends- 
ville, Concord (T.V.A. 138-SW) Quadrangle; McMullens, Meadow (T.V.A. 
139-NW) Quadrangle; at the Gulley Cemetery, 0.4 mile northeast of St. Clair, 
Bulls Gap (T.V.A. 171-SE). Quadrangle. 
Fetzer tongue in Tennessee: At the bend of the road 0.6 mile south-southeast 
of Harrison-Chilhowie Academy, Walden Creek (T.V.A. 156-SW) Quadrangle. 
Little Oak formation in Alabama: On the point of the ridge, 1 mile south- 
west of Newhope Church, Vandiver (15’) Quadrangle; 2 miles north of Pelham, 
Bessemer Iron District (15’) Quadrangle; cut on the L. and N. RR., ¢ mile 
northwest of Mosteller, Columbiana (15’) Quadrangle. 
“Lenoir” formation=Little Oak in Alabama: East of Leeds, Leeds (15’) 
Quadrangle. 
Pratt Ferry formation: 0.2 mile southeast of Pratt Ferry, Blocton (15’) 
Quadrangle. 
Discussion—This is the largest and most robust of the species of this genus. 
A few specimens only are known, but these show the species to be somewhat 
variable in its convexity. Beside its great size this species differs from the 
others described in the evenness of its lateral profile. 
TITANAMBONITES CONVEXUS Cooper, new species 
Plate 178, A, figures 1-8 
Shell of about medium size for the genus, wider than long, with the hinge 
equal to or wider than the width at the middle; sides sloping by a gentle curve 
