PLATE XXXIX. 
a. Central lateral space of area. 1. Outside lateral and middle lateral muscle 
a’. Outer lateral space of area. sears on dorsal valve. 
f. Flexure line of area. p. Pedicle groove. 
h. Central muscle sear. s. Median septum. 
i. Transmedian muscle scar. y. Visceral cavity. 
j. Anterior lateral muscle sear. vs. Main vascular sinus. 
LINGULELLA WANNIECEI Redlich (p. 538). 
Ficure 1. Elongate form of the ventral valve. U.S. Nat. Mus. Cat. No. 517440. 
ja, 1b, and 1c. Short, broad, subtriangular forms of the ventral valve. U.S. Nat. Mus. Cat. Nos. 51744a, 
51744b, and 51744c, respectively. 
1d. Cast of the interior of a ventral valve, showing the area, visceral area, and vascular sinuses. U.S. Nat. 
Mus. Cat. No. 51744d. 
le. Imperfect interior of a ventral valve. U.S. Nat. Mus. Cat. No. 51744e. : 
1f. Dorsal valve in position against the ventral valve, showing the area of the ventral valve. U.S. Nat. Mus. 
Cat. No. 517441. 
1g, lh, and li. Exteriors of dorsal valves, varying somewhat in outline. U.S. Nat. Mus. Cat. Nos. 51744g, 
51744h, and 517441, respectively. 
1j and 1k.- Interiors of imperfect dorsal.valves. U.S. Nat. Mus. Cat. Nos. 51744j and 51744k, respectively. 
11. Interior of a remarkably well preserved dorsal valve. U.S. Nat. Mus. Cat. No. 517441. 
Im. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51744m. 
In. Interior of a dorsal valve, showing anterior lateral scars and narrow ridges in the position of the main 
vascular sinuses. U.S. Nat. Mus. Cat. No. 51744n. 
. 
"The specimens represented are all from Locality 15r, Middle Cambrian argillaceous shale at Khussak, Salt Range, 
India. 
LINGULetya Fucus! Redlich (p. 502). 
Figure 2. Narrow elongate form which may be compared with figure 3. U.S. Nat. Mus. Cat. No. 51746a. 
2a. Cast of a very small dorsal valve. U.S. Nat. Mus. Cat. No. 51746b. 
2b and 2c. Dorsal valves referred to this species. U.S. Nat. Mus. Cat. Nos. 51746c and 51746d, respectively. 
3. Ventral valve, the type specimen. Copied from Redlich [1899, Pl. I, fig. 10c]. 
The specimens represented are all from Locality 15r, Middle Cambrian argillaceous shale at Khussak, Salt Range, 
India. 
’ LINGULELLA IssE (Walcott) (p. 509). 
[Text figs. 43A-F, p. 510.] 
Fieures 4and 4a. Narrow and broad forms of ventral valves, with exterior shell partly exfoliated. U.S. Nat. Mus. 
Cat. Nos. 51808a and 51808b, respectively. Figure 4a represents the type specimen. 
4a’. Side outline of specimen represented by figure 4a. 
4b and 4b’. Exfoliated dorsal valve and side outline. U.S. Nat. Mus. Cat. No. 51808c. 
The specimens represented are all from Locality 15d, Upper Cambrian limestone near Cave Spring, Fish Spring 
Range, Utah. ; 
OBOLUS MCCONNELLI PELIAS (Walcott) (p. 398). 
[Pl. XXII, figs. 3b-c.] 
Figure 5. Ventral valve with outer layer of shell exfoliated, from Locality 15p, Middle Cambrian limestones near the 
north end of the Fish Spring Range, Utah. U.S. Nat. Mus. Cat. No. 51597a. 
da and 5b. Partly exfoliated dorsal valves associated with the specimen represented by figure 5. U.S. 
Nat. Mus. Cat. Nos. 51597b and 51597c, respectively. 
dc. A dorsal valve doubtfully referred to this species, from Locality 7s, Upper Cambrian shale 4 miles south- 
southeast of Emigrant Peak, Silver Peak quadrangle, Nevada. U.S. Nat. Mus. Cat. No. 51593a. 
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