Manasa Devi is mentioned in the Vedas as Serpent Queen, particularly in the Rig Veda Brahmanas.
The Vedas say: "...thereby he wins the brilliance that is in the serpent..."
Explanation of a few terms
Samhita is the basic metrical (mantra) text of each of the Vedas. The Brahmanas are commentaries on the four Vedas. They detail the proper performance of rituals. Some other ancient texts contain references to the Sarpa Veda that deals with the science of serpents. It originated in the east. There were more Brahamanas in the past, as each Vedic shakha or school used its own Brahmana. Aitareya Brahmana and Kaushitaki Brahmanas are associated with the Rig Veda, the oldest of the Vedas. The Brahmanas are part of the Vedas, the Hindu Shruti literature - the cosmic sound that the authors of these texts heard. Puranas belong to a different category - Smriti - the cosmic sound that was remembered.
Here we see the crescent moon in the shape of a smiling letter C turned to the left (the symbol of Manasa) on the image of an ancient European snake goddess.
Nilangu is a Sankrit term that refers to "species of worm".
The Rig Veda, one of the oldest religious books of the world, refers to Sarpa Ranji (Serpent Queen). She was one of the female authors of the parts of the Rig Veda. The Yajur Veda has the following text (in Prapathaka V, The Piling of the Fire Altar): "Thou art the eastern quarter, the favorable by name; of thee as such Agni is the overlord, the black (snake) the guardian". Or: "...of thee as such Varuna is overlord, the striped snake." Or: "...of thee as such Yama is the overlord, the spotted necked (snake) the guardian..." Or: "To Indra, the king, a boar; to Varuna, the king, a black (antelope); to Yama, the king, a deer; to the bull, the king, a Gayal; to the tiger, the king, a Bos Gavaeus; to the king of men a monkey; for the swift falcon a quail; for the Nilangu (snake) a worm; for Soma, the king, a gazelle; for the ocean a crocodile; for the snowy mountain an elephant." In Yajur Veda (Taittiriya Sanhita) we will also find the following: "With the verses of the queen of serpents he establishes the Garhapatya (a ritual or yajna was compulsory in the Vedic times), and so renewing it he establishes it as immortal."
The Gopatha Brahmana of the Atharva Veda speaks about serpents
too. Sarpa Vidya (science of snakes) is mentioned in Satapatha
and Gopatha Brahmanas. Aligi is the name of a kind of snake
in the Atharva Veda (V-13-7). In the Vedas - see
the source - it is written: "They sing
the verses of the serpent queen on that day."