There is no feminine word which is declined like स्त्री because 1-4-4 नेयङुवङ्स्थानावस्त्री specifically excludes स्त्री (which means स्त्री can take the आदेश: इयँङ् and also keep the नदी-संज्ञा). Also 6-4-79 स्त्रियाः and 6-4-80 वाऽम्शसोः are specific to the प्रातिपदिकम् स्त्री.

Questions:
1. Which पुंलिङ्ग-प्रातिपदिकम् that we studied also has a unique declension? Which are the rules that make it unique?

2. In this verse Sb11-16-13 from श्रीमद्भागवतम् what is the विभक्तिः and वचनम् of विष्णू in the second line? How was it formed?
इन्द्रोऽहं सर्वदेवानां वसूनामस्मि हव्यवाट् ।
आदित्यानामहं विष्णू रुद्राणां नीललोहितः ।।