Can You Cast Mass Cure Wound On Someone Who Has Been Swallowed by a creature?

Mass Healing Word and other healing spells specifically say that you have to see someone in order to cast the spells. Mass Cure Wounds just says that you choose a point and then choose 6 creatures within a 30 foot radius. Do you need to see a creature in order to choose them? For example, would you be able to cast it on someone who had been swallowed?