1: yellow salivary gland on either side of radula tube secretes mucus to lubricate action of radula and cement food particles together.
2: yellow buccal mass contains odontophore that supports active end of radula.
In this image, buccal mass and salivary gland are pushed forwards into snout making it yellowish. Height 2.2 mm, Llŷn Peninsula, Wales. March ,2015.