PLATE XLIX. 
a. Central lateral space of area. 
c. Trapezoidal area, including central, middle 
. Middle lateral muscle sear. 
. Outside lateral muscle scar. 
dove 
lateral, and outside lateral muscle scars. . Pedicle groove. 
h. Central muscle scar. . Visceral cavity. 
i. Transmedian muscle scar. vs. Main vascular sinus. 
j. Anterior lateral muscle sear. x. Heart-shaped cavity. 
Oxsotus (WesTonrIA) ESCASONI (Matthew) (p. 459). 
Ficure 1. Cast of the interior of a ventral valve, showing continuation of cast of pedicle furrow, with the central 
depression of the visceral area. University of Toronto, Canada. 
la. Interior of ventral valve, showing heart-shaped cavity and position of central muscle scars; also a strongly 
pitted and striated interior surface. University of Toronto, Canada. Type specimen, figured by 
Matthew [1901a, Pl. V, fig. 1g] as Lingulella (?) escasoni. 
Jaa. Enlargement of the central portion of figure 1a to show the position and size of the muscle scars, surface 
pits, etc. : 
1b. Cast of the interior of a rather large dorsal valve. University of Toronto, Canada. Specimen is probably 
the one illustrated by Matthew [1901a, Pl. V, fig. 1d] as Lingulella (?) escasoni. 
1c, 1d, and le. Interior of dorsal valves, showing the position of muscle scars. University of Toronto, Canada. 
1f. Enlargement of the exterior surface of a shell 3 mm. long, to show radiating striz, lines of growth, and 
transverse undulating lines. University of Toronto, Canada. 
The figures are all drawn from specimens in Matthew’s figured material, but except in the cases noted (figs. la 
and 1b) identification is impossible. The specimens represented are all from Locality 325, Upper Cambrian shales on 
McAdam Shore, East Bay, Cape Breton, Nova Scofia. 
Osotus (WEsTONIA) STONEANUS (Whitfield) (p. 465). 
[Pl. XXVII, figs. 2, 2a-g.] 
Ficure 2. A dorsal valve from Locality 11¢, Upper Cambrian sandstone near Newton, New Jersey. 
2a. Enlargement of the exterior surface of the specimen represented by figure 2. 
The specimen represented was figured by Weller [1903, Pl. T, fig. 6] as Lingulella stoneana. 
LINGULELLA TEXANA Walcott (p. 535). 
Ficure 3. Partly exfoliated dorsal valve, showing strong radiating striz which characterize the species. Locality 
69, Upper Cambrian limestone near Honey Creek, Burnet County, Texas. U. 8. Nat. Mus. Cat. 
No. 51805a. 
3a. Cast of a dorsal valve, the type specimen, showing the area and muscle scars. Locality 70, Upper Cam- 
brian limestone near Morgans Creek, Burnet County, Texas. U.S. Nat. Mus. Cat. No. 51806a. Copied 
from Walcott [1908d, Pl. VIII, fig. 5]. 
Osotus (Westonta) reais Walcott (p. 462). 
Ficures 4 and 4’. Ventral valve from which the outer layer of shell has been exfoliated. Locality 64, Upper Cam- 
brian limestone near the Bullwhacker mine, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 
51720a. ; 
4a and 4a’. Partly exfoliated dorsal valve from Locality 201a, Lower Ordovician limestone east of Ham- 
burg Ridge, Eureka district, Nevada. U.S. Nat. Mus. Cat. No. 51542a. 
4b. Dorsal valve preserving most of the outer layer of the shell, the type specimen, associated with the 
shell represented by figure 4a. U.S. Nat. Mus. Cat. No. 51542b. 
4c. Dorsal valve associated with the shell represented by figure 4. U.S. Nat. Mus. Cat. No. 51720b. 
4d. Enlargement of a portion of the outer surface of the shell represented in figure 4b. U. 8. Nat. Mus. 
Cat. No. 51542b. 
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