PLATE LIX. 
a. Area. s. Median septum. 
el. Cardinal sears. v. Visceral area. 
F!, Cast of foraminal tube. vs. Vascular sinus. 
BorsrorDiaA C#®LATA (Hall) (p. 603). 
[Pl. LIX, figs. 3, 3a-b.] 
Fietre 1. Partly exfoliated, broken ventral valve from Locality 20, Lower Cambrian limestone bowlders at entrance 
FIGURE 
FIGURE 
to Bic Harbor, Quebec, Canada. U.S. Nat. Mus. Cat. No. 35259a. 
la. Fragment of a large ventral valve from Locality 2b, Lower Cambrian limestone north of Beman Park, near 
Troy, New York. U.S. Nat. Mus. Cat. No. 52040a. 
1b. Top, side, and back views of a ventral valve associated with the shell represented by figure la, showing 
the foraminal aperture. U.S. Nat. Mus. Cat. No. 52040b. 
1c. Broad form of ventral valve from Locality 27, Lower Cambrian limestone in the eastern suburb of Troy, 
New York. U.S. Nat. Mus. Cat. No. 15325a. Specimen figured [Walcott, 1886b, Pl. VII, fig. lb] as 
Lingulella cxlata. 
1d. Small ventral valve associated with the shell represented by figure 1. U.S. Nat. Mus. Cat. No. 35259b. 
le. Cast of part of the interior of a ventral valve from Locality 2p, Lower Cambrian limestone a little west of 
Bic, Quebec, Canada. U.S. Nat. Mus. Cat. No. 56874a. 
1f. Interior of a small ventral valve from Locality 35a, Lower Cambrian limestone on Bald Mountain, Washing- 
ton County, New York. U.S. Nat. Mus. Cat. No. 52037a. 
1g. Fragment of the interior of a ventral valve from Locality 29a, Lower Cambrian limestone at Schodack, 
Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 15323a. s 
lh. Enlargement ofa portion of the exterior surface of a ventral valve associated with the specimen represented 
by figurel. U.S. Nat. Mus. Cat. No. 35259c. 
li. Partly exfoliated dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. 
Cat. No. 52040c. 
1j. Posterior portion of a dorsal valve associated with the specimen represented by figure la. U.S. Nat. Mus. 
Cat. No. 52040d. 
1k. Cast of the posterior portion of the interior of a dorsal valve associated with specimen represented by figure 
la. U.S. Nat. Mus. Cat. No. 52040e. 
11. Partly exfoliated dorsal valve from Locality 35, Lower Cambrian limestone 1.5 miles north of Bald Moun- 
tain, Washington County, New York. U.S. Nat. Mus. Cat. No. 17457a. 
Im. Partly exfoliated dorsal valve associated with the specimen represented by figure la, showing cast of the 
median sepium and main vascular sinuses. U.S. Nat. Mus. Cat. No. 52040f. 
In. Fragment of a cast of the interior of a dorsal valve. The true outline of this specimen and the locality are 
unknown. Am. Mus. Nat. Hist., New York. : 
Jo. Enlargement of surface of a dorsal valve associated with the specimen represented by figure Ie. U.S. 
Nat. Mus. Cat. No. 15325b. Specimen figured [Walcott, 1886b, Pl. VII, fig. 1d] as Lingulella czxlata. 
1p and 1p’. Thin section of limestone containing many shells of the species from Locality 2b, Lower Cambrian 
limestone north of Beman Park, Troy, New York. U.S. Nat. Mus. Cat. No. 52040g. 
lq. Exfoliated ventral valve showing cast of pedicle opening and visceral cavity, from Locality 29a, Lower 
Cambrian limestone at Schodack, Rensselaer County, New York. U.S. Nat. Mus. Cat. No. 15323b. 
MicKWITzIA MONILIFERA (Linnarsson) (p. 330). 
[PI. VI, figs. 1, la-p.] 
2. Top and side views of the posterior portion of a ventral valve from Locality 396v, Lower Cambrian sandstone 
below the cement factory on Kunda Brook, Government of Esthonia, Russia. U.S. Nat. Mus. Cat. 
No. 51522a. 
BorsrorDiA CLATA (Hall) (p. 603). 
[Pl. LIX, figs. 1, la-q.] 
3 and 3a. Top and back views of a ventral valve from Locality 39a, Lower Cambrian limestone north of Easton 
Station, Washington County, New York. U.S. Nat. Mus. Cat. No. 52039a. 
3b. Interior of a dorsal valve from Locality 38, Lower Cambrian limestone 3 miles west of South Granville, 
Washington County, New York. U.S. Nat. Mus. Cat. No. 52038a. 
196 
