272 PLATE LXXXI. 
ORBICULOIDEA PILEOLUS (Hicks MS.) (Salter) (p. 722). 
Fiaure 11. Exterior of ventral valve, the type specimen, from Locality 318d, Middle Cambrian, Menevian sand- 
stones at Porth-y-rhaw, St. Davids, South Wales. Copied from Davidson [1868, Pl. XVI, fig. lla]. 
lla. Exterior of dorsal valve from the locality represented by figure 11. Copied from Davidson [1868, Pl. 
XVI, fig. 12a]. 
ACROTHELE LEVISENSIS Walcott (p. 646). 
Ficur®r 12. Exterior of a compressed ventral valve, the type specimen. Geol. Survey Canada: Copied from Walcott 
[1908d, Pl. VIII, fig. 13}. 
12a. Exterior of a compressed dorsal valve. Geol. Survey Canada. 
12b. Cast of the interior of a dorsal valve. Geol. Survey Canada. 
The specimens represented are all from Locality 319a, Lower Ordovician Levis shales at Point Levis, Quebec, 
Canada. 
