The transverse ocarina is originally from Italia, Budrio near Bologna.(see more here)
The fingering has many similarities with the flute and it has the strongest sound of the ocarina family. With one an a half octave range mostly (a few notes more for the piccolo and a few less for the bass) it allows many different music styles, even classical music.
You can see my friend Cyrille Mercadier at work :
A. Vivaldi – Concerto in Do Maggiore Op.10 (RV 443) – Sextuor Denner
Vivaldi “la tempesta di mare” : Octuor Denner
Vivaldi concerto in A minor RV 108, 1st mvt with Ocarina