Grayia smithii
Grayia smithii, Smith's African water snake, is a species of snake in the family, Colubridae. It is found in Equatorial Guinea, Cameroon, the Democratic Republic of the Congo, the Republic of the Congo, Gabon, Central African Republic, Zambia, South Sudan, Uganda, Kenya, Tanzania, Rwanda, Burundi, Nigeria, Benin, Togo, Ghana, Ivory Coast, Liberia, Guinea, Guinea-Bissau, Senegal, Burkina Faso, Sierra Leone, Gambia, Niger, Chad, and Angola.

References 

Grayia
Snakes of Africa
Reptiles of Equatorial Guinea
Reptiles of Cameroon
Reptiles of the Democratic Republic of the Congo
Reptiles of the Republic of the Congo
Reptiles of Gabon
Reptiles of the Central African Republic
Reptiles of Angola
Reptiles of Zambia
Reptiles of South Sudan
Reptiles described in 1818
Taxa named by William Elford Leach