The feminine affix ūṅ comes in denoting a Name after the words 1. kadru 'tawny' 2. kamaṇḍalu 'a water pot'.,
This rule applies to other than Vedic forms. Thus कद्रूः 'a female named Kadru wife of Kasyapa', कमण्डलूः 'Kamandalu'. Why do we say \in denoting a Name\? Observe कद्रूः 'the tawny color.' कमण्डलूः 'a water-gourd'.,