Valmiki Ramayana Sundara Kanda Sarga 56 Shloka 30

अतिप्रमाणाः very big ones in size, बलिनः strong ones, दीप्तजिह्वाः with glowing tongues, महाविषाः highly poisonous, महाहयः huge snakes, निपीडितशिरोग्रीवाः pressed on their heads and necks, व्यचेष्टन्त started protruding.

Highly powerful, huge and poisonous snakes with their glowing tongues protruded, pressed on their heads and necks (by Hanuman).