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EXHIBIT 3.1.15
LIBERTY PROPERTY LIMITED PARTNERSHIP
PARTNERSHIP INTERESTS
AS OF DECEMBER 31, 2004
<Table>
<Caption>
NUMBER OF
PARTNERSHIP
LIMITED PARTNERS INTERESTS %
- ------------------------------------------ ------------ ------------
1 Balitsaris, Peter 58,542 0.0620%
2 Carr, Clai 115,000 0.1218%
3 Castorina, John 14,491 0.0153%
4 Denny, Joseph 260,250 0.2756%
5 Felix, Jill 195,043 0.2066%
6 Fenza, Robert 195,043 0.2066%
7 Fitzgerald, Ward 14,491 0.0153%
8 Gildea, Larry 93,319 0.0988%
9 Goldschmidt, Robert 22,895 0.0242%
10 Hagan, Michael 14,491 0.0153%
11 Hammers, David 244,426 0.2589%
12 Kiel, Bob 14,491 0.0153%
13 Kline, Earl 19,128 0.0203%
14 Lutz, Jim 37,312 0.0395%
15 Mazzerralli, James 14,491 0.0153%
16 Messaros, Sharron 7,245 0.0077%
17 Morrissey, Mary Beth 14,491 0.0153%
18 Price, Leslie 99,970 0.1059%
19 Reichert, Joseph 27,242 0.0288%
20 Estate of Willard Rouse 460,418 0.4876%
21 Trust for Congdon Children 95,347 0.1010%
22 Trust for Hammers Children 95,348 0.1010%
23 Trust for Mary Rouse 13,621 0.0144%
24 Trust for Anne Rouse 13,621 0.0144%
25 Trust for Rouse Younger Children 81,726 0.0865%
26 Trust for Laurie Hammers 5,506 0.0058%
27 Weitzmann, Mike 42,312 0.0448%
28 Liberty Special Purpose Trust 10,574 0.0112%
29 Thomas, Rebecca 8,076 0.0086%
30 Trust for J. Ryan Lingerfelt 15,625 0.0165%
31 Trust for Justin M. Lingerfelt 15,625 0.0165%
32 Trust for Daniel K. Lingerfelt 15,625 0.0165%
33 Trust for Catherine E. Lingerfelt 15,625 0.0165%
34 Lingerfelt, Alan T 317,500 0.3362%
35 Lingerfelt, L. Harold 164,375 0.1741%
36 Lingerfelt, David L 30,674 0.0325%
37 Ferguson, Morris U 6,000 0.0064%
</Table>
EXHIBIT 3.1.15
LIBERTY PROPERTY LIMITED PARTNERSHIP
PARTNERSHIP INTERESTS - CONTINUED
AS OF DECEMBER 31, 2004
<Table>
<Caption>
NUMBER OF
PARTNERSHIP
LIMITED PARTNERS INTERESTS %
- ------------------------------------------ ------------ ------------
38 Lingerfelt, Carl C 10,900 0.0115%
39 Wright, Murray H 7,500 0.0079%
40 Latimer, Erle Marie 12,500 0.0132%
41 Samet, Norman G 14,013 0.0148%
42 Mann, Bernard 14,012 0.0148%
43 Stender, Stewart R 57,613 0.0610%
44 Rouse & Associates Maryland Partnership 20,000 0.0212%
45 Helwig, A. Carl 299,737 0.3174%
46 Sunday, James J 79,348 0.0840%
47 Walters, Charles J 230,723 0.2443%
48 Doyle, Margaret A 19,380 0.0205%
49 Stanford Baratz Revocable Trust 9,044 0.0096%
50 F. Greek Logan Properties, LLC 33,682 0.0357%
PREFERRED LIMITED PARTNERS
- ------------------------------------------
51 Belair Real Estate Corporation 1,510,000 1.5991%
52 Belrose Realty Corporation 700,000 0.7413%
53 Bel Alliance Properties, LLC 1,590,000 1.6839%
54 Montebello Realty Corp. 800,000 0.8472%
55 JPM Mosaic VI REIT, Inc. 473,000 0.5009%
GENERAL PARTNER
- ------------------------------------------
56 Liberty Property Trust GP 90.7320%
------------
Total Ownership 100.0000%
</Table>
GP - The partnership units for Liberty Property Trust have not been
reflected because there is no conversion of units to shares by the
general partner.