430 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
species of which are close homeomorphs of Campylorthis, abounds in the Appa- 
lachians. 
Chaulistomella is a variable genus in its exterior form, some of the species hav- 
ing the deeply concave pedicle valve similar to that of Campylorthis, but others 
are more like Multicostella in exterior form. As far as known, none of them has 
been found with a pseudodeltidium in place. 
CAMPYLORTHIS DEFLECTA (Conrad) 
Plate 69, A, figures 1-6 
Strophomena deflecta Conran, Proc. Acad. Nat. Sci. Philadelphia, vol. 1, p. 332, 1843. 
S. recta ConraD, ibid., p. 332. 
Plaesiomys loricula Hatt and CLarKe, Pal. New York, vol. 8, pt. 1, pp. 197, 341, pl. 5A, 
figs. 31-34, 1892. 
For complete biblography, see Bassler, U. S, Nat. Mus. Bull. 92, p. 442, 1915. 
Valcourea deflecta (Conrad) ScHUCHERT and Cooper, Mem. Peabody Mus. Nat. Hist., vol. 4, 
pt. I, p. 97, 1932. 
Shell fairly large, subelliptical in outline; hinge generally narrower than the 
shell width at the middle; cardinal extremities acute in the young, obtusely 
rounded in the adult; sides gently rounded; anterior margin broadly rounded ; 
anterior commissure strongly uniplicate ; lateral margin strongly deflected toward 
the brachial valve; surface costellate, costellae broadly rounded and separated 
by striae narrower than the costellae; about Io costellae in 5 mm. at the front 
margin of a large adult. 
Pedicle valve unevenly concave in lateral profile, with the umbonal region 
gently convex but the anterior two-thirds fairly deeply concave; anterior profile 
broadly concave; umbo narrowly convex, the convexity extended anteriorly to 
about the middle as a low fold; valve deeply sulcate anterior to the middle; flanks 
deflected toward the pedicle valve and therefore concave; cardinal extremities 
prominently deflected toward the brachial valve; interarea strongly apsacline to 
catacline ; delthyrium covered by a large convex pseudodeltidium. Interior with 
small teeth having deep fossettes; muscle field squarish in outline with promi- 
nent adjustor scars at the base of the dental plates; diductor scars prominent; 
pallial impressions not strongly marked. 
Brachial valve unevenly convex in lateral profile, the umbo flattened, the 
median region moderately convex and the front somewhat flattened; anterior 
profile strongly convex with the greatest convexity in the median region and 
with steep and abrupt lateral slopes. Umbo flattened but sulcate; sulcus nar- 
row, shallow, extending to the middle where it disappears into a more or less 
prominent fold of the anterior half; median and anterior regions forming a 
broad fold with the flanks sloping strongly to the margins. Posterolateral areas 
concave with outer side deflected toward the brachial direction. Interarea long 
and flat, orthocline with a prominent chilidium. Notothyrial platform strongly 
thickened; median ridge occupying the posterior third; brachiophores stout; 
cardinal process moderately long and thick; pallial marks not deeply impressed. 
