— 
PLATE LX. 201 
ACROTHELE GAMAGEI (Hobbs) (p. 645). 
Ficures 5 and 5’. Top view and side outline of a ventral valve 
5a. Cast of the interior of a ventral valve 
U.S. Nat. Mus. Cat. No. 
5b and 5b’. 
U.S. Nat. Mus. Cat. No. 51986b. 
Partly exfoliated specimen of a dorsal valve and side outline of same. 
of Comparative Zoology; cast in the United States National Museum 
dc. Cast of the interior of a dorsal valve. U.S. Nat. Mus. Cat. No. 51986c. 
The specimens represented are all from Locality 5, Middle Cambrian siliceous shale on Hayward Creek, Braintree, 
Massachusetts. 
51986a. 
Original in the Museum 
(Cat. No. 51987a). 
ACROTHELE WOODWORTHI Walcott (p. 661) 
FIGure 6 
. Top, back, and side views of a cast made from the outer surface of a natural mold from Locality 326c, 
Lower Cambrian limestone at Nahant, Essex County, Massachusetts. Type specimen in the col- 
lection of the Boston Society of Natural History; cast in the United States National Museum (Cat 
No. 52030a). Copied from Walcott [1908d, Pl. IX, fig. 11]. 
ACROTHELE TURNERI Walcott (p. 660). 
Ficures 7 and 7’ 
Top and side views of a partly crushed ventral valve, the type specimen, from Locality 7r, Middle 
Cambrian shales 4 miles south-southeast of Emigrant Peak, Esmeralda County, Nevada. U.S. Nat. 
Mus. Cat. No. 52028a. Copied from Walcott [1908d, Pl. IX, figs. 12 and 12/]. 
7a. Exterior of a compressed dorsal valve associated with the specimen represented by figure 7 
U.S. Nat. 
Mus. Cat. No. 52028b. 
ACROTHELE SUBSIDUA (White) (p. 656). 
[Pl. LX, figs. 1, 1a-o.] 
Figure 8. Large compressed ventral valve from Locality 14s, Middle Cambrian Ogugopsis zone on Mount Stephen, 
British Columbia. U.S. Nat. Mus. Cat. No. 24063a. 
ACROTHELE SUBSIDUA HERA Walcott (p. 659). 
Ficures 9 and 9’. Top and side views of an exfoliated ventral valve, the type specimen, showing the concentric 
striz and radiating ridges on the inner layers of the shell. From Locality 31a, Lower Cambrian 
limestone near Pioche, Nevada. U.S. Nat. Mus. Cat. No. 52024a. Copied from Walcott [1908d, PI. 
VIII, figs. 15 and 157]. 
