982 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Types.—Holotype: 118041a; figured paratypes: 117264a-c, 117265a,b,d,f, 
h,k,p; unfigured paratypes: 117265¢,e,g,i,j,l-0,q, 117266a-h. 
Horizon and locality.—Arline formation (lower-middle) in Concord (T.V.A. 
138-SW) Quadrangle, Tennessee: In glade + mile southeast of Friendsville; 
100 yards southwest of the Negro Cemetery, 4 mile northeast of Friendsville. 
Discussion.—Fine silicified specimens of this species occur at Friendsville. Al- 
though the silicification is coarser than that of some of the other genera at this 
place, it is sufficiently good to yield excellent study material. The important 
specific characters are the ornamentation, well-developed sulcus which originates 
at the umbo, the well-developed apical plate, and the ponderous cardinalia. The 
ornamentation is stronger than that of L. pionodema, the apical plate is better 
developed, and the cardinalia more robust. 
LATICRURA MAGNA Cooper, new species 
Plate 144, B, figures 26-29; plate 145, C, figures 20-23 
Shell large, subcircular in outline, with the greatest width at the middle; hinge 
narrower than the greatest width; sides and anterior margin broadly rounded; 
costellae fine and crowded, appearing in several generations, about 4 to the milli- 
meter at the anterior margin of the holotype. 
Pedicle valve most convex in the umbonal region when seen in lateral view; 
anterior portion somewhat flattened. Anterior profile with median region nar- 
rowly rounded and with long, fairly gentle slopes to the margins. Interarea 
strongly apsacline, beak short and slightly incurved. 
Brachial valve most convex at the umbo in lateral profile; broadly convex in 
anterior profile. Beak prominent; umbo swollen; sulcus originating at the beak, 
narrow and shallow and extending to the anterior margin. Flanks gently swollen. 
Measurements in mm.—Holotype, length 10.5, brachial length 10.0, width 
13.7, hinge width 11.0, thickness ?. 
Types.—Holotype: 117267a; figured paratypes: 117267b, 117268a; unfigured 
paratypes: 117267c, 117268b,c. 
Horizon and locality—Oranda formation in Virginia: 0.6 mile northwest of 
Linville, Broadway (15’) Quadrangle. On the railroad 4 mile west of Strasburg ; 
Lee Highway (U. S. 11), 14 miles southwest of Strasburg; Strasburg (15’) 
Quadrangle. 
Same formation in Pennsylvania: 1 mile north of Guilford Springs, Chambers- 
burg (15’) Quadrangle. 
Martinsburg formation (part with Brongniartella=Salona) in Virginia: On 
Virginia Highway 617=910, 0.15 mile north of Green Mount Church, Broadway 
(15’) Quadrangle. 
Discussion.—This species is distinguished from the others herein described 
by its much greater size, and its strongly apsacline, almost procline interarea, 
slightly incurved beak, and sides sloping rapidly toward the middle. The species 
is a rare shell at all localities where it has been seen. 
