saptadaśe — vanapathe mathurā-gamana
aṣṭādaśe — vṛndāvana-vihāra-varṇana
saptadaśe - in the Seventeenth Chapter; vana-pathe - through the forest path; mathurā-gamana - Lord Caitanya Mahāprabhu's going to Mathurā; aṣṭādaśe - in the Eighteenth Chapter; vṛndāvana-vihāra-varṇana - description of His touring the forest of Vṛndāvana.