Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
तपास्तपस्य क्रमशश्चैत्रादीनां समाह्वयाः ।यस्मिन्मासे पौर्णमासी येन धिष्ण्येन संयुता ॥ १३१ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 131.
Tapas and Tapasya complete them. These are the names of Chaitra and the rest, in order. The month in which the full moon is joined with a certain star ...
Simple meaning: Tapas and Tapasya are the last two month names. The rest of the sentence runs into the next verse.
तन्नक्षत्राह्वयो मासः पौर्णमासी तदाह्वया ।
A month is named after the star its full moon sits in. Its two fortnights are the bright and the dark.
शुभाशुभे कर्मणि च प्रशस्तौ भवतः सदा ।
The two fortnights are both praised for acts. The first five moon days are ruled by Brahma, Agni, Virinchi, Vishnu and Shailaja.
विनायकयमौ नागचंद्रौ स्कंदोऽर्कवासवौ ।
This verse lists more gods who rule the moon days in order.