PLATE V. 
a. Pseudo-area. p. Pedicle opening. 
h, Central muscle scar. s. Median septum. 
j. Anterior lateral muscle scar. vy. Visceral area. 
vs. Main vascular sinus. 
KurorGina crIncuLATA (Billings) (p. 580). 
(Text figs. 3, p. 299, 8, p. 299, and 50A-C, p. 581.] 
Ficure 1. Top and side view of a partly exfoliated ventral valve from Locality 25a, Lower Cambrian limestone, 2 
miles east of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337a. Specimen figured by Walcott 
[1886b, Pl. IX, fig. 1d; and 189la, Pl. LXIX, fig. 1d]. 
la. Side view of the two valves united, from Locality 25a, near Swanton, Vermont. U.S. Nat. Mus. Cat. No. 
15337b. Specimen figured by Walcott [1886b, Pl. IX, fig. 1c; and 189la, Pl. LXIX, fig. 1c]. 
1b 1c, and 1d. Side, ventral, and dorsal views of a nearly entire shell, natural size, from Locality 26a, near 
Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15337d. Specimen figured by Walcott [1886b, Pl. IX, 
figs. 1, la-b; and 1891la, Pl. LXIX, figs. 1, la-b]. 
Je and 1f. Side and dorsal views of a younger shell than that represented by figures 1b, 1c, and 1d, but from 
the same locality. U.S. Nat. Mus. Cat. No. 15336a. 
lg. Exfoliated dorsal valve, showing central muscle scars and radiating vascular canals. From Locality 
392a, Lower Cambrian limestones at L’Anse au Loup, Labrador. U.S. Nat. Mus. Cat. No. 14893a. 
th. Interior of a dorsal valve from Locality 2a, Lower Cambrian limestone, 2 miles east of Swanton, Vermont, 
showing muscle scars and vascular canals. U.S. Nat. Mus. Cat. No. 15337c. Specimen figured by 
Walcott [1886b, Pl. IX, fig. 1f; and 189la, Pl. LXIX, fig. 1]. 
li. Exterior of a dorsal valve from Locality 25a, Lower Cambrian, 2 miles cast of Swanton, Vermont. U.S. 
Nat. Mus. Cat. No. 15337f. Specimen figured by Walcott [1886b, Pl. LX, fig. le; and 1891a, Pl. LXTX, 
fig. le]. 
1j. Exterior and side views of a fine ventral valve from Locality 20, Lower Cambrian limestone, Bic Harbor, 
Province of Quebec, Canada. U.S. Nat. Mus. Cat. No. 51510a. 
1k and 1k’. View of area and side view of a ventral valve from Bic Harbor (Locality 20). U.S. Nat. Mus. 
Cat. No. 51510b. 
1land 1m. Exterior views of two dorsal valves from Bic Harbor (Locality 20). U.S. Nat. Mus. Cat. Nos. 
51510c and 51510d, respectively. 
In. View of pseudo-area beneath apex of an elevated ventral valve from Locality 25a, Lower Cambrian lime- 
stone, 2 miles east of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15336b. 
lo. Transverse section of the two valves in natural position, from Swanton, Vermont (Locality 25a). The gaping 
; pedicle opening is’ well shown. U.S. Nat. Mus. Cat. No. 15336c. 
lp. Enlargement of a cross section of a fragment of the shell from Locality 25a, Swanton, Vermont. U.S. 
Nat. Mus. Cat. No. 15337e. 
1q. Enlargement of a longitudinal section of the shell at the apex of the ventral valve. Locality 26a, Lower 
Cambrian, 2 miles east of Swanton, Vermont. U.S. Nat. Mus. Cat. No. 15336d. 
Irand Is. Exterior of ventral and dorsal valves from Locality 392a, Lower Cambrian limestone at L’Anse 
au Loup, Straits of Belleisle, Labrador, Canada. U. S. Nat. Mus. Cat. Nos. 14893b and 14893c, 
respectively. . 
KurorGina PECULIARIS (Tate) (p. 583). 
Figure 2. Top view of type specimen, a dorsal valve, from Locality 31a, Middle? Cambrian, at Ardrossan, Yorke 
Peninsula, South Australia. Original in the collection of the University of Adelaide, Adelaide, 
South Australia. Cast in the United States National Museum (Cat. No. 58300). Spetimen figured 
by Tate [1892, Pl. II, fig. 5] as Orthis (?) peculiaris. 
Kuroreina PERUGATA Walcott (p. 583). 
Figure 3. Exterior and side view of an exfoliated ventral valve. U.S. Nat. Mus. Cat. No. 5151la. The outline of 
the visceral area is drawn from another specimen. U.S. Nat. Mus. Cat. No. 51511g. 
3a. Top and side views of a less elongate ventral valve than that represented by figure 3. U.S. Nat. Mus. 
Cat. No. 51511b. 
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