| Number | Class/Group | Characteristics |
|---|---|---|
| 1 | Первозвери (Prototheria) | Egg-laying mammals. |
| 2 | Сумчатые (Metatheria) | Marsupials; young are born underdeveloped and complete development in a pouch. |
| 3 | Насекомоядные (Insectivora) | Insectivorous mammals. |
| 4 | Рукокрылые (Chiroptera) | Bats; flying mammals. |
| 5 | Грызуны (Rodentia) | Rodents; characterized by continuously growing incisors. |
Note: The table appears to be a classification of mammal groups, with common names in Russian. The characteristics are briefly described based on general biological knowledge of these groups.