24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
a variable one. Chonetes monosensis Cooper (1953) is also suggestive 
because of its fine ornamentation but its brachial valve is even flatter 
than that of the Oregon one. 
The Oregon specimens indicate a variable species or possibly more 
than one species. The specimen from S68 is best preserved and has 
both valves. The sulcus of the pedicle valve is shallow but a specimen 
from U.O. 2201-3 has the same form but a deep sulcus. The specimen 
is much exfoliated and this may emphasize the depth of the sulcus. 
However, a specimen from S111 is flatter and with a shallower sulcus. 
The description above was composed on the basis of the complete 
specimen, and the above comparisons were made with it. 
Chonetes phosphoriensis Branson (1930) is similar internally to 
the Oregon species, Branson’s figure 6 on plate 5 being very like the 
impression of the pedicle valve from Si11. His species, however, 
appears to be more strongly costellate than the Oregon specimens. 
CHONETES PYGMOIDEUS Cooper, new species 
Plate 1H, figures 19-26 
Shell small for the genus, subcircular in outline with maximum 
width at the middle, well-rounded sides and anterior margin; surface 
costellate, costellae numbering about 5 to the millimeter. 
Pedicle valve strongly convex in lateral profile, especially in the 
umbonal region which is strongly swollen ; anterior profile strongly and 
narrowly convex; median region strongly inflated; sulcus originating 
on the umbo, shallow but fairly broad and extending to the anterior 
margin; flanks not prominent; lateral slopes steep. Beak strongly 
incurved, overhanging the moderately long and curved interarea. 
Brachial valve nearly flat in both profiles; umbonal region fairly 
deeply concave forming a subcircular pit under the beak; fold orig- 
inating on the anterior side of the pit, low and widening moderately 
to the anterior margin; flanks and cardinal extremities flattened. 
Measurements in mm.—Holotype, length 10.0, brachial length 7.7, 
maximum width 11.2, hinge width 6.7, thickness 4.9, height 5.1. 
Type.—Holotype, U.S.N.M. 125469. 
Locality.— S30. 
Discussion—The shape and general expression of this shell sug- 
gest an abnormal specimen, but study of it indicates that it is normal 
but of unusual shape for a chonetid. Chonetes timanicus Tscherny- 
schew is of about the same size and shape but it is more deeply sulcate. 
