PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 837 
nate; ornamentation obscure because of poor preservation but of the usual type 
in the genus, consisting of a mat of fine costellae separated into groups by stronger 
ones. 
Pedicle valve unevenly convex in lateral profile; the visceral or posterior part 
very slightly convex; trail moderately long; angle of geniculation about 100°. 
Geniculation occurring about 9 mm. anterior to the beak. Umbonal region 
slightly convex but most of visceral area flattened; trail slopes steep. Muscles 
deeply inserted. 
Brachial valve with visceral region nearly flat, umbo concave, and anterior 
sharply geniculated toward the brachial valve ; deepest part at place of genicula- 
tion. Interior with strongly developed ridge at the place of geniculation ; adduc- 
tor blades well developed. 
Measurements in mm.— 
Brachial Hinge Thick- Surface Trail 
Length length Midwidth width ness length length 
Holotype ....... 12.6 11.3 22.9 23.0-+- ? ? 7.0+ 
Batatype «kets fs 14.7 ? 21.0 23.6 Fy 20.0 10.0 
Types.—Holotype: 117604b; unfigured paratype: 117604a. 
Horizon and locality— Botetourt formation in Virginia: Between U. S. High- 
way 60 and Whistle Creek from 1 to 2} miles northwest of Lexington, Lexington 
(15’) Quadrangle. 
Discussion.—This species is characterized by its steep trail and transversely 
rectangular outline. Its form is like D. geniculaia, but it is larger and more trans- 
verse. Its resemblance to D. prona is strong, but comparison with that species 
is difficult because details of the brachial valve are unknown. Nevertheless, 
D. prona appears to be a much less transverse species than the Botetourt form. 
DACTYLOGONIA sp. 1 
Plate 228, C, figure 19 
The material of this species consists of a poorly preserved and incomplete 
adult and an interior of the pedicle valve. The species was large, having a 
visceral area extending 13 mm. anterior to the beak. The trail is mostly missing. 
The interarea is short, and the specimen is quite thin. Thus the species was 
large and thin bodied. 
The pedicle interior indicates short but flaring dental plates with short and 
narrow umbonal cavities. The muscle field is moderately large and subcircular 
in outline; the diductors are flabellate ; the adductor scars are somewhat elongate 
and separated anteriorly by a low ridge. The remainder of the interior is sparsely 
papillose. 
Figured specimen.—117605. 
Horizon and locality—Benbolt formation in Virginia: 4 mile north of the 
school at Rye Cove, Clinchport (T.V.A. 188-NW) Quadrangle. 
Same formation in Tennessee: About 0.1 to 0.2 mile north of the road, 1.4 miles 
northeast of Lee Valley, Pressmens Home (T.V.A. 171-NE) Quadrangle. 
