954 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Measurements in mm.—Holotype, length 15.1, brachial length 15.1, midwidth 
20.6, hinge width 13.8, thickness 3.6. 
Types.—Holotype: 116964a; figured paratype: 116964b. 
‘Horizon and locality—Lower Hermitage formation in Tennessee: Along 
Tennessee Highway 53, 1 to 14 miles south-southeast of Woodbury (15’) 
Quadrangle. 
Discussion —The generic identity of this species has caused considerable diffi- 
culty. The species was at first thought to be a member of the Dinorthidae but 
flakes of the shell heated in a blast lamp showed definite punctae. As a dalmanel- 
lid the genus Onniella seems the most likely assignment at the present time, but 
the species is resupinate and is the only member of the genus Onmniella having 
this profile. It is probable that the species belongs to a genus not yet described. 
Paratype 116964b was roasted in a blast lamp and part of the shell pealed 
off to reveal the pedicle muscle field. This proved to be subquadrate, but details 
of the brachial interior were not clear because of partial silification of the shell 
and crystallinity of the matrix. The brachial processes are flat blades like those 
of Onniella. 
ONNIELLA FERTILIS (Ulrich) 
Plate 157, A, figures 1-3; plate 157, C, figures 5, 6; plate 150, E, figures 21-37 
Orthis (Dalmanella) testudinaria Hayes and UtricH (not Dalman), U. S. Geol. Surv., 
folio 95, Illustr. Sheet, figs. 42, 43, 1903. 
Orthis (Dalmanella) fertilis Ulrich in BASsLer, Virginia Geol. Surv. Bull. 2A, p. 182, pl. 24, 
fig. 5, 1909. 
Shell large for the genus, planoconvex ; width about 13 times the hinge width; 
posterolateral extremities narrowly rounded ; sides moderately rounded ; anterior 
margin strongly rounded ; anterior commissure rectimarginate to slightly sulcate. 
Costellae generally 2 to 1 mm. at the front margin, in places 3 to the millimeter. 
Pedicle valve gently convex in lateral profile with the maximum convexity in 
the umbonal region; anterior profile broadly triangular, the median region nar- 
rowly convex to carinate with long, gently dipping lateral slopes. Beak small, 
low ; umbo narrowly convex, the convexity continued anteriorly as an indistinct 
fold; interarea short, curved, apsacline. 
Brachial valve nearly flat in both profiles; umbo narrowly sulcate, the sulcus 
extending anteriorly to the front margin but scarcely widening anteriorly ; lateral 
regions gently concave to nearly flat; posterolateral extremities flattened and 
deflected slightly toward the pedicle valve. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Hypotype (117360a)......... 16.0 15.3 20,1 12,0 4.5 
% CR ETSO0RL) «Sita a aioe 12.8 12.3 15.8 [Ls 5.0 
Types.—Lectotype: 96362b; paratypes: 96362a,c,d; figured hypotypes: 
117369a-d, 123238a,b. 
Horizon and locality—Curdsville formation in Virginia: On U. S. High- 
