PLATE XCIV. 
EoortHis wWIcHITAENSIS (Walcott) (p. 790). 
[PI. XCIV, fig. 1u.] 
Fieures 1 and 1’. Exterior of ventral valve, the type specimen, and view of area, from Locality 12p, Upper Cam- 
brian limestones, at the northwest extremity of the Arbuckle Mountains, about 4 miles (6.4 km.) east 
of Homer, Carter County, Oklahoma. U.S. Nat. Mus. Cat. No. 52384a. 
laand 1a’. Exterior of ventral valve showing slight mesial fold, with side view. Locality 12k, Upper Cambrian 
limestones in sec. 35, T. 1 S., R. 1 E., Ardmore quadrangle, Carter County, Oklahoma. U. S. Nat. 
Mus. Cat. No. 52383a. 
1b and 1b’. Exterior of ventral valve associated with the specimen represented by figure 1, showing 
flattened mesial area. U.S. Nat. Mus. Cat. No. 52384b. 
le and Ic’. Exterior of ventral valve associated with the specimen represented by figure la. U.S. Nat. Mus. 
Cat. No. 52383b. 
1d. Exterior of ventral valve from Locality 71, Middle Cambrian limestone in Cold Creek Canyon, Burnet 
County, Texas. U.S. Nat. Mus. Cat. No. 52379a. 
le. Ventral valve partly exfoliated posteriorly so as to show cast of muscle area, associated with the 
specimen represented by figure 1. U.S. Nat. Mus. Cat. No. 52384c. 
lf. Exterior of ventral valve, with straight cardinal slopes, associated with the specimen represented by 
figure 1. U.S. Nat. Mus. Cat. No. 52384d. ' 
1g and 1h, lh’. Exterior views of two dorsal valves illustrating variation in form and surface characters, 
associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. Nos. 52384e and 52384f, 
respectively. 
li. Exterior of dorsal valve associated with the specimen represented by figure 1d. U.S. Nat. Mus. Cat. 
No. 52379b. 
1j, 1)’, and lk. Exteriors of two dorsal valves associated with the specimen represented by figure la. U.S. 
Nat. Mus. Cat. Nos. 52383c and 52383d, respectively. 
1land 1m. Dorsal valves associated with the specimen represented by figure 1. U.S. Nat. Mus. Cat. Nos. 
52384g and 52384h, respectively. 
In. Dorsal valve from Locality 12n, Upper Cambrian limestones in sec. 1, T. 2 8., R. 1 E., Ardmore quad- 
rangle, Carter County, Oklahoma. U.S. Nat. Mus. Cat. No. 52381a. 
lo. Cast of interior of a dorsal valve from Locality 68, Upper Cambrian limestone in Packsaddle Mountain, 
Llano County, Texas. U.S. Nat. Mus. Cat. No. 52382a. 
EoorRTHIS WICHITAENSIS L&ViuscuLusS (Walcott) (p. 791). 
Fieures Ip, lq, ly, and 1s. Ventral, dorsal, side, and posterior views of the type specimen, a complete shell free from 
matrix, from Locality 12p, Upper Cambrian limestones, at the northwest extremity of the Arbuckle 
Mountains, about 4 miles (6.4 km.) east of Homer, Carter County, Oklahoma. U.S. Nat. Mus. Cat. 
No. 52396a. 
EoortHis INDIANOLA (Walcott) (p. 780). 
[Pl]. XCIV, figs. 2, 2a-h.] 
Ficure 1t. Dorsal valve from Locality 12k, Upper Cambrian limestones, Ardmore quadrangle, Carter County, Okla- 
homa. U.S. Nat. Mus. Cat. No. 52348a. 
Figure lu. Fragment of limestone from Locality 14b, Upper Cambrian limestone on Cold Creek, Llano County, Texas, 
illustrating association of forms of Hoorthis wichitaensis (W) and Hoorthis indianola (X). U.S. Nat. 
Mus. Cat. No. 52380a. 
EoortHiIs WICHITAENSIS (Walcott) (p. 790). 
(Pl. XCIV, figs. 1, la-o.] 
Ficure lu. Fragment of limestone from Locality 14b, Upper Cambrian limestone on Cold Creek, Llano County, Texas, 
illustrating association of forms of Hoorthis wichitaensis (W) and Eoorthis indianola (X). U.S. Nat. 
Mus. Cat. No. 52380a. : 
