SB 4.1.61

tebhyo ’gnayaḥ samabhavan
 catvāriṁśac ca pañca ca
ta evaikonapañcāśat
 sākaṁ pitṛ-pitāmahaiḥ
tebhyaḥ — from them; agnayaḥ — fire-gods; samabhavan — were produced; catvāriṁśat — forty; ca — and; pañca — five; ca — and; te — they; eva — certainly; ekona-pañcāśat — forty-nine; sākam — along with; pitṛ-pitāmahaiḥ — with the fathers and grandfather.
From those three sons another forty-five descendants were generated, who are also fire-gods. The total number of fire-gods is therefore forty-nine, including the fathers and the grandfather.

The grandfather is Agni, and the sons are Pāvaka, Pavamāna and Śuci. Counting these four, plus forty-five grandsons, there are altogether forty-nine different fire-gods.