Heads of white rhinoceros (Ceratotherium simum) (left) and black rhinoceros (Diceros bicornis).
Date 1913
Source Catalogue of the ungulate mammals in the British Museum (Natural History) (1913) https://archive.org/details/catalogueofungul05brit
Author Richard Lydekker (1849-1915)
Source: https://commons.wikimedia.org/wiki/File:Heads_of_White_Rhinoceros_and_Black_Rhinoceros.jpg

* Square-lipped rhinoceros (Ceratotherium simum)
The white rhinoceros, white rhino or square-lipped rhinoceros (Ceratotherium simum) is the largest extant species of rhinoceros. It has a wide mouth used for grazing and is the most social of all rhino species. An alternative name for the white rhinoceros, more accurate but rarely used, is the square-lipped rhinoceros. Order: Perissodactyla > Family: Rhinocerotidae > Genus: Ceratotherium > Species: Ceratotherium simum

* Hook-lipped rhinoceros (Diceros bicornis)
The black rhinoceros, black rhino or hook-lipped rhinoceros (Diceros bicornis) is a species of rhinoceros, native to eastern and southern Africa. Although the species is referred to as black, its colours vary from brown to grey. It is the only extant species of the genus Diceros. Order: Perissodactyla > Family: Rhinocerotidae > Genus: Diceros > Species: Diceros bicornis