PART)'T CHAZYAN AND RELATED BRACHIOPODS—COOPER 209 
Genus WESTONIA Walcott, 1901 
WESTONIA CLATHRATA (Winchell and Schuchert) 
Plate 1, A, figures 1, 2 
Lingula clathrata WINCHELL and ScHucHERT, Geol. Minnesota, vol. 3, p. 345, pl. 20, fig. 42, 
1803. 
Shell small, thin, longitudinally elliptical in outline. Lateral margins broadly 
rounded ; anterior margin narrowly rounded. Greatest width at the middle or 
slightly anterior to the middle. Beak angle about 90°. Surface marked by strong 
concentric undulations which are crossed by transverse, subparallel lines that 
swing slightly posteriorly at the middle to form a broad and shallow V. Trans- 
verse lines most prominent on the flanks and body of the shell in the posterior 
two-thirds, the anterior third being marked by such lines only on the lateral 
slopes. 
Pedicle valve with umbonal and median region somewhat swollen; greatest 
depth in the posterior third ; anterior slope long and gentle ; umbonal slopes short 
and steep. Anterior profile gently convex. 
Brachial valve somewhat more convex than the pedicle one in both profiles. 
Lateral profile gently convex but anterior profile moderately arched ; beak mar- 
ginal; lateral slopes fairly strong; anterior slope gentle. 
Measurements in mm.— 
Length Width 
MECRLOUU Pe |CrACKIAl VaANVG)\ cc's 0. soit ceca ane dere Sees queue 3.6 2.0 
Paratype’ (pedicle:walve"45546a)) 0. kA Pe ee 4.5 2.3+ 
Types.—Lectotype: 45546b; figured paratype: 45546a; unfigured paratypes: 
45546c-l. 
Horizon and locality—Decorah formation (Guttenberg member-Rhinidictya 
bed) in Minnesota: At St. Paul. 
Discussion.—This species is characterized by its small size and peculiar orna- 
mentation. The transverse lines are fairly distant, about 4 to the millimeter on 
the shell edge, and crowding only slightly medially. The posterior swing in the 
lines is shallow and separates this species easily from the others here assigned 
to this genus. 
Details of the interior are so difficult to determine from the specimens availa- 
ble that it is not possible to decide the type of hinge region in the two valves. 
WESTONIA SUPERBA Cooper, new species 
Plate 11, E, figures 9, 10 
Shell of about medium size for the genus, known from the brachial valve only. 
Elongate, oval in outline, sides diverging anteriorly, nearly straight; anterior 
margin narrowly rounded. Beak and umbo smooth; remainder of valve marked 
by concentric, narrowly rounded, low costellae, nearly parallel on the margins 
but swinging posteriorly to form a quincunxial pattern on the median region. 
Strongly convex medially with long and moderately steep lateral slopes. Interior 
