768 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Types.—Lectotype: 66168a; paratypes: 66168b-d; figured hypotypes: 
110948a-c,f, 110949a,c. 
Horizon and locality—Oranda formation in Strasburg (15’) Quadrangle, 
Virginia: In the railroad cut $ mile west of Strasburg; on U. S. Highway 11, 
from 4 to 2 miles southwest of Strasburg; on Virginia Highway 55, 0.4 mile 
west of U. S. Highway 11, north edge of Strasburg. 
Same formation in Pennsylvania: 1 mile northwest of Guilford Springs, 
24 miles southwest of Chambersburg, Chambersburg (15’) Quadrangle. 
Discussion—This species is more transverse and never attains the large size 
reached by B. superba and B. buttsi. It was originally confused with Christiania 
and under that term lent an erroneous name to a stratigraphic zone. Inasmuch 
as the Oranda formation is nearly synonymous with the Christiania or Bimuria 
zone, it is really not necessary to use the generic names. 
Bimuria lamellosa is a fairly small species which will not be confused with 
B. buttsi or B. superba. It is not unlike B. parvula but differs in its larger size, 
stronger and more inflated umbo, and more completely lamellose exterior. 
BIMURIA ? MATUTINA Cooper, new species 
Plate 210, C, figures 6-10 
Small, resembling B. immatura, wider than long with the greatest width at or 
near the hinge; sides oblique, gently rounded ; anterior margin broadly rounded ; 
surface smooth in the decorticated condition but showing traces of lamellae in 
distant, elevated concentric lines. 
Pedicle valve moderately strongly convex, flattened in the anterior third and 
narrowly rounded on the umbo; anterior profile with median region strongly 
humped and with long, moderately steep and gently concave lateral slopes. Um- 
bonal and median regions strongly swollen, the swelling continued anteriorly but 
in diminishing degree to the front margin. Sides depressed and with moder- 
ately steep anterolateral slopes. Foramen and interarea not observed; interior 
unknown. 
Brachial valve deeply concave, with the deepest part at or just posterior to 
the middle. Concavity occupying most of valve and resulting anterior margin 
strongly reflected in the direction of the brachial valve. Cardinal extremities 
concave. Interior unknown. 
Measurements in mm.— 
Brachial Hinge Thick- 
Length length Midwidth width ness Height 
Holotype: s .22l) .ahsiets. <2 4.9 ? 6.5 oi) ? 2.3 
Paratype (66288a)...... 5.7 2 8.3 8.8? ? 21 
¥ (66288e)iifo 5. ? 4.1 6.7 7.4 ? ? 
Types.—Holotype: 66288b; figured paratype: 66288a; unfigured paratypes: 
66288c-g. 
Horizon and locality—Boulder in the Mystic Conglomerate in Canada: On 
Range 6, Lot 20, Stanbridge Township, near Mystic, Quebec. 
