| Ladd-Franklin, Christine |
0678 |
| Lane, Jonathan Homer |
0414 |
| Langley, Samuel Pierpont |
0534, 0599, 0647, 0660, 0722, 0857 |
| Laplace, Pierre-Simon |
0147 |
| Lavoisier, Antoine-Laurent |
0007 |
| Lawson, Andrew Cowper |
0890 |
| Lazear, Jesse W. |
0754 |
| Lazzaroni |
0296, 0314 |
| Lea, Isaac |
0186 |
| Leavitt, Henrietta Swan |
0873 |
| LeConte, John |
0346 |
| LeConte, John L. |
0097, 0571 |
| LeConte, Joseph |
0302, 0509 |
| Leidy, Joseph |
0251, 0264, 0274, 0399, 0422, 0526 |
| Lesley, J. Peter |
0335 |
| Lesquereux, Leo |
0328, 0535, 0573 |
| Lesueur, Charles |
0097, 0125 |
| Levene, Phoebus Aaron |
0893 |
| Lewis and Clark expedition |
0051, 0062, 0078, 0177 |
| Lewis, Gilbert Newton |
0904 |
| Lewis, Meriwether |
0051 |
| Lick Observatory |
0467, 0601, 0670, 0709, 0750, 0918 |
| Lick, James |
0467 |
| Liebig, Justus von |
0213, 0236 |
| Lillie, Frank Rattray |
0888 |
| Linnaean Society of New England |
0080 |
| Linnaean Society of Philadelphia |
0055 |
| Literary and Philosophical Society of Charleston, S.C. |
0079 |
| Literary and Philosophical Society of New York |
0082 |
| Little, Arthur D. |
0592 |
| Lloyd, Curtis G. |
0583 |
| Lloyd, John Uri |
0583 |
| Locke, John |
0273 |
| Loeb, Jacques |
0748, 0856 |
| Long, Crawford Williamson |
0228 |
| Long, Stephen H. |
0111 |
| Loomis, Elias |
0234, 0359 |
| Loomis, Mahlon |
0398 |
| Lowell Institute (Boston) |
0200, 0255 |
| Lowell, Francis Cabot |
0081 |
| Lowell, Percival |
0692, 0825, 0840 |
| Lusk, Graham |
0841 |
| Lyceum of Natural History of New York |
0094 |
| Lyman, Benjamin Smith |
0400 |
| Lyman, Chester Smith |
0394 |
