75 
Corbulat onestae n. sp. 
Plate XIV, figures 1-4 
This is a small, subquadrate, moderately convex species. The anterior 
margin rounded, basal margin little rounded, posterior margin long, almost 
straight and inclined, and the dorsal margin long, sloping a little on either 
side of the beak. Beak one-third to one-quarter from anterior end. Post- 
umbonal slope angular near the umbo and rounded postero-ventrally in 
shells of mature size. The surface has even, concentric striae, with occas- 
ional stronger striae, or constrictions. The hinge of the left valve has two 
small cardinal teeth directed backward and between them a deep socket. 
There is also a long posterior lateral and a short anterior lateral. 
The general form and outline suggest a Corbula , but it is not so produced 
postero-ventrally. The dentition is not that of Corbula. Onesta is the 
name of a chief of the Blackfeet Indians. 
Height of holotype 7-5 mm., length 10 mm. 
Horizon and Locality. In the Hillcrest Unio bed of the Blairmore 
formation and in the same formation on Lyon creek about 520 feet above 
the base. 
Types. National Museum of Canada; holotype, Cat. No. 9032; 
paratypes, Cat. Nos. 9032a, b, 9033. 
Corbula ? palliseri n. sp. 
Plate XIV, figure 5 
A small semiquadrate species. The anterior margin rounded, ba,sal 
margin a little curved, the posterior margin long, nearly straight and 
inclined to dorsal margin, and the dorsal margin long, but shorter than the 
total length of the shell. Beak a little in front of the middle. Postum- 
bonal slope sharply angular. Surface covered with relatively coarse, even 
costae. This species is smaller than Corbula perundata Meek and Hayden 1 , 
does not narrow posteriorly, and has finer costae. It is probably not a 
Corbula and congeneric with Corbula ? onestae n.sp. 
Length 6 mm., height 4*5 mm. 
Horizon arid Locality. About 520 feet above the base of the Blair- 
more formation on Lyon creek and in the Unio bed on the hill south of 
Hillcrest. 
Type. National Museum of Canada; holotype, Cat. No. 9034. 
COLORADO SHALE SPECIES 
Martesia mcevoyi n.sp. 
Plate XV, figures 1-3 
Shell of moderate size; euneate in outline. High and swollen anter- 
iorly, narrow and compressed posteriorly; about twice as long as high. 
Ventral margin long; anterior margin rounded; dorsal margin about one- 
half length of shell, inclined forwards a little to the ventral margin; postero- 
dorsal margin long, very slightly rounded, and inclined at an angle of about 
1 Proc. Acad. Nat. Sci., Pliila., 8, for 1850, p. 116. 
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