These pendulous green grapes ($2.99 per pound), like the panelle, arancini, and many other items at Valentino, have an Italian provenance. (My barber, Alberto, pointed the way to his local market.) On their shipping boxes they were branded simply "moscat," presumably, a variation on "muscat."
Almost all muscat cultivars are spheroidal. These, as you see, were proportioned like the familiar sultanas, also known as Thompson seedless, but they were considerably heftier, and I quickly discovered that their seeds were fully formed. My best guess is that these were muscats of Alexandria, but I invite further intel.
Valentino Food Market
66-64 Fresh Pond Rd. (at Madison St.), Ridgewood, Queens