νομίσας ἔμεινεν ὡς ἕτοιμα δειπνήσων
There is some irregularity in this line: the - ας is probably elided to fit the metre.
Babrius very frequently puts an anapest (short short long) on the first foot. You can imagine those first two shorts resolving to make the foot a spondee, which is one of the allowed first feet.
Equivalently x _ . _ where x can resolve to (. .)
Even in 5th-cent. tragedy anapests are acceptable in the first foot (especially in Euripides), and in Babrius there is no inhibition against them there (unlike in the other feet).
ok got it thanx