Wiktionary
large-headed water snake
n. ''Natrix megalocephala'', a species of snake in the Colubridae family
Wikipedia
Large-headed water snake
The large-headed water snake (Natrix megalocephala) is a species of snake in the Colubridae family. It is native to the Caucasus region and has been recorded in Azerbaijan, Georgia, Russia, and Turkey.
N. megalocephala was added to Annex II of the Convention on the Conservation of European Wildlife and Natural Habitats in 1996 but as of 2005 taxonomic studies have recommended this taxon for removal as it may not be genetically distinct from N. n. natrix.