In a sandhi sequence like devÄn+tatra, according to P 8.3.7 (naÅ›chavyapraÅ›Än), the word final n changes into ru, which changes into visarga and ultimately into s. The vowel before the n becomes optionally nasalized by P 8.3.2 (atrÄnunÄsikaḥ pÅ«rvasya tu vÄ), and in the alternative that it does not become nasalized, it is followed by an anusvÄra by P.8.3.4 (anunÄsikÄt paro 'nusvÄraḥ). The rule P 8.3.36 (vÄ Å›ari) says that a word-final visarga optionally remains a visarga before Å›, á¹£, and s, while the VÄrttika (kharpare Å›ari vÄ lopo vaktavyaḥ) stipulates that if the following Å›, á¹£ and s are followed by a khaR sound (i.e. kh, ph, ch, á¹h, th, c, á¹, t, k, p, Å›, á¹£, or s, then the visarga is optionally deleted. Your example अमà¥à¤·à¥à¤®à¤¿à¤‚ सà¥à¤¤à¤µà¥‡, and the observations of Whitney, MacDonell and Coulson seem to relate to the variation noted by these rules of PÄṇini and the VÄrttika. There are quite a few options involved, and they reflect the variation in the usage. Best,
Madhav
Madhav M. Deshpande
Professor Emeritus
Sanskrit and Linguistics
University of Michigan
[Residence: Campbell, California]