| Oligoryzomys fulvescens subsp. lenis (Goldman, 1915) |
| Oligoryzomys fulvescens subsp. mayensis (Goldman, 1918) |
| Oligoryzomys fulvescens subsp. pacificus (Hooper, 1952) |
| Ondatra Link, 1795 |
| Ondatra zibethicus (Linnaeus, 1766) |
| Ondatra zibethicus subsp. bernardi Goldman, 1932 |
| Ondatra zibethicus subsp. ripensis (Bailey, 1902) |
| Onychomys Baird, 1858 |
| Onychomys arenicola Mearns, 1896 |
| Onychomys arenicola subsp. ater S. Anderson, 1972 |
| Onychomys arenicola subsp. canus Merriam, 1904 |
| Onychomys arenicola subsp. surrufus Hollister, 1914 |
| Onychomys leucogaster (Wied-Neuwied, 1841) |
| Onychomys leucogaster subsp. albescens Merriam, 1904 |
| Onychomys leucogaster subsp. longipes Merriam, 1889 |
| Onychomys leucogaster subsp. ruidosae Stone & Rehn, 1903 |
| Onychomys longicaudus Merriam, 1889 |
| Onychomys longipes Merriam, 1889 |
| Onychomys macrotis Elliot, 1903 |
| Onychomys ramona Rhoads, 1893 |