EXHIBIT 99.1

February 17, 2010

XTO Energy Inc.

810 Houston Street, Suite 2000

Fort Worth, TX 76102

Gentlemen:

At your request, Miller and Lents, Ltd. (MLL) estimated the proved reserves and future net revenues as of December 31, 2009, attributable to the XTO Energy Inc. (XTO) interest in certain oil and gas properties prior to inclusion in the Cross Timbers Royalty Trust, i.e., Underlying Properties (100%). The properties consist of approximately 2,970 leases and 15,278 wells and are located in New Mexico, Oklahoma, and Texas.

MLL performed evaluations, which are designated as the SEC Pricing Case, using price and expense premises specified by XTO and described in detail on Attachment 1. The aggregate results of MLL’s evaluations are as follows:

Proved reserves and future net revenues were estimated in accordance with the provisions contained in Securities and Exchange Commission Regulation S-X, Rule 4-10(a). The Securities and Exchange Commission definition of proved reserves is shown on Attachment 2. Gas volumes for each property are stated at the pressure and temperature bases appropriate for the sales contract or state regulatory authority. Therefore, some of the aggregated totals may be stated at a mixed pressure base. No provisions for the possible consequences, if any, of product sales imbalances were included in MLL’s projections since we received no relevant data. Estimates of future net revenues and discounted future net revenues are not intended and should not be interpreted to represent fair market values for the estimated reserves. In MLL’s projections, future costs of abandoning facilities and wells were assumed to be offset by salvage values. Estimated costs, if any, for restoration of producing properties to satisfy environmental standards are beyond the scope of this assignment.

Following Attachment 2 is a list of exhibits that include annual projections of future production and net revenues for each reserves category, interest type, and state. Also included in the exhibits are one-line summaries showing the proved reserves and future net revenues for each property in the total royalty trust, in the working interest category, in the royalty interest category, and in each state. Projections of individual property future production and net revenues are included in separate volumes to this report. These exhibits and volumes should not be relied upon independently of this narrative.

The proved developed producing reserves and production forecasts were estimated by production decline extrapolations, water-oil ratio trends, P/Z declines, or in a few cases, by volumetric calculations. For some properties with insufficient performance history to establish trends, MLL estimated future production by analogy with other properties with similar characteristics. The past performance trends of many properties were influenced by production curtailments, workovers, waterfloods, and/or infill drilling. Actual future production may require that MLL’s estimated trends be significantly altered. Reserves estimates from volumetric calculations and from analogies are often less certain than reserves estimates based on well performance obtained over a period during which a substantial portion of the reserves was produced.

The data employed in MLL’s estimations of proved reserves and future net revenues were provided by XTO. The current expenses for each lease were obtained from operating statements provided by XTO except for certain leases where XTO deducted items considered by XTO to be nonrecurring expenditures. No overhead was included for those properties operated by XTO. For some properties, such as large waterfloods, XTO assumed a decline in operating costs due to depleting production that was derived by forecasting a decrease in the property well count. None of the data provided to MLL by XTO, including, but not limited to, graphical representations and tabulations of past production performance, well tests and pressures, ownership interests, prices, and operating costs, were verified by MLL as such was not within the scope of our assignment.

The evaluations presented in this report, with the exceptions of those parameters specified by others, reflect MLL’s informed judgments based on accepted standards of professional investigation but are subject to those generally recognized uncertainties associated with interpretation of geological, geophysical, and engineering information. Government policies and market conditions different from those employed in this

study may cause the total quantity of oil or gas to be recovered, actual production rates, prices received, or operating and capital costs to vary from those presented in this report.

Miller and Lents, Ltd. is an independent oil and gas consulting firm. No director, officer, or key employee of Miller and Lents, Ltd. has any financial ownership in XTO Energy Inc. or any related company. MLL’s compensation for the required investigations and preparation of this report is not contingent on the results obtained and reported, and we have not performed other work that would affect our objectivity. Preparation of this report was supervised by an officer of Miller and Lents, Ltd., who is a professionally qualified and licensed Professional Engineer in the State of Texas with more than 25 years of relevant experience in the estimation, assessment, and evaluation of oil and gas reserves.

MLL’s work papers and data are in our files and available for review upon request. If you have any questions regarding the above, or if we can be of further assistance, please call.

JCP/slc

February 17, 2010

Attachment 1

12/31/09

Cross Timbers Royalty Trust (100%)

SEC PRICING CASE

Attachment 2

Page 1

Reserves Definitions In Accordance With

Securities and Exchange Commission Regulation S-X

Reserves

Reserves are estimated remaining quantities of oil and gas and related substances anticipated to be economically producible, as of a given date, by application of development projects to known accumulations. In addition, there must exist, or there must be a reasonable expectation that there will exist, the legal right to produce or a revenue interest in the production, installed means of delivering oil and gas or related substances to market, and all permits and financing required to implement the project.

Reserves should not be assigned to adjacent reservoirs isolated by major, potentially sealing, faults until those reservoirs are penetrated and evaluated as economically producible. Reserves should not be assigned to areas that are clearly separated from a known accumulation by a non-productive reservoir (i.e., absence of reservoir, structurally low reservoir, or negative test results). Such areas may contain prospective resources (i.e., potentially recoverable resources from undiscovered accumulations).

Proved Oil and Gas Reserves

Proved oil and gas reserves are those quantities of oil and gas, which, by analysis of geoscience and engineering data, can be estimated with reasonable certainty to be economically producible—from a given date forward, from known reservoirs, and under existing economic conditions, operating methods, and government regulations—prior to the time at which contracts providing the right to operate expire, unless evidence indicates that renewal is reasonably certain, regardless of whether deterministic or probabilistic methods are used for the estimation. The project to extract the hydrocarbons must have commenced or the operator must be reasonably certain that it will commence the project within a reasonable time.

Attachment 2

Page 2

Developed Oil and Gas Reserves

Developed oil and gas reserves are reserves of any category that can be expected to be recovered:

Undeveloped Oil and Gas Reserves

Undeveloped oil and gas reserves are reserves of any category that are expected to be recovered from new wells on undrilled acreage, or from existing wells where a relatively major expenditure is required for recompletion.

Analogous Reservoir

Analogous reservoirs, as used in resources assessments, have similar rock and fluid properties, reservoir conditions (depth, temperature, and pressure) and drive mechanisms, but are typically at a more advanced stage of development than the reservoir of interest and thus may provide concepts to assist in the interpretation of more limited data and estimation of recovery. When used to support proved reserves, an “analogous reservoir” refers to a reservoir that shares the following characteristics with the reservoir of interest: