Exhibit
23.3
[Ryder
Scott Company, L.P. Letterhead]
CONSENT
OF INDEPENDENT PETROLEUM ENGINEERS AND GEOLOGISTS
The
undersigned hereby consents to the references to our firm in the form and
context in which they appear in the Annual Report on Form 10-K/A of St. Mary
Land & Exploration Company for the year ended December 31,
2007. We hereby further consent to the use of information contained
in our reports, as of December 31, 2007, setting forth estimates of revenues
from St. Mary Land & Exploration Company’s oil and gas
reserves. We further consent to the incorporation by reference
thereof into this Registration Statement on Form S-8.
/s/
RYDER SCOTT COMPANY, L.P.
Ryder
Scott Company, L.P.
Denver,
Colorado
June 19,
2008