74 
long, almost straight. Beaks anterior, Postumbonal slope abruptly 
rounded and shell surface above it rather narrowly inflected. On umbones 
ornamented with moderately sized, even concentric costae which die out 
ventrally and actually cover only a small part of the surface. Above the 
postumbonal slope these costae bend upwards with a sharp angle and on 
the umbones are straight, but posteriorly they become angular and irregular 
and disappear toward the posterior end. 
Length 51 mm., height 26 mm. 
Unio vetustus 1 Meek and U. douglassi 2 Stanton have two radiating 
sharp ribs on the postumbonal slope and lack the irregular and angular 
costae which occur above the postumbonal slope of U. hamili. 
The species name is given for the late C. B. Hamil, an assistant on the 
Geological Survey, Canada. 
Horizon and Locality. In the Unio bed of the Blairmore formation, 
on the hill south of Hillcrest. 
Types . National Museum of Canada; holotype, Cat. No. 9029; 
paratypes, Cat. Nos. 9029a, b. 
Unio cf. hamili n. sp. 
Plate XIII, figures 5, 6 
A few small, immature specimens from Lyon creek have the sculpture 
of the umbonal part of this species, except that the costae are somewhat 
finer and more closely arranged. 
Horizon and Locality , On Lyon creek in the Blairmore formation, 
about 230 feet above the base. 
Types. National Museum of Canada; types, Cat. Nos. 9030, 9030a. 
Unio sp. 
Plate XIV, figure 10 
The ornament of this species is not well preserved, but on the umbo 
are small concentric ribs and near the dorsal margin posterior to the beak 
there is what appears to be a short radiating carina, above which the con- 
centric ribs bend upwards. The ornament is thus similar to Unio douglassi 
Stanton and related species. The ribbing, however, is finer than in U. 
douglassi and the ornament does not extend so far beyond the umbo as in 
U. douglassi. The Blairmore shell is also much more elongate and the 
surface is narrowly and abruptly inflected along the dorsal margin. This 
is probably a new species, but as the ornament is imperfectly preserved, 
it is not named. 
Length 79 mm., height 25 mm. 
Horizon and Locality. In the Blairmore formation from the Unio 
bed on hill south of Hillcrest. 
Type. National Museum of Canada; type, Cat. No. 9031. 
1 Proc. Acad, Nat, Sci., Phila., for I860, p. 312. 
* Stanton, T. W.: Proc. Am. Phil. Soc., 42, 1903, p. 195, PI. 4, figs. 3, 4. 
