The final a of pāda is elided when it is at the end of a bahuvrīhi samāsa preceded by a word denoting a thing with which it is compared but not so when such word is hasti etc.,
The word उपमानात् is understood here. The लोप substitution is a samasanta affix in a way. Thus व्याघ्रस्येव पादावस्य = व्याघ्रपात्, सिंहपात् ॥ But हस्तिपादः, कटोलपादः ॥
1 हस्तिन्, 2 कुदाल, 3 अश्व, 4 कशिक, 5 कुरुत, 6 कटोल, 7 कटोलक, 8 गण्डोल, 9 गण्डोलक, 10 कण्डोल, 11 कण्डोलक, 12 अज, 13 कपोत , 14 जाल, 15 गण्ड, 16 महेल, (महिला), 17 दासी, 18 गणिका, 19 कुसूल ॥,