1. The first part is 1/2 Circulate;
2. The last part is Centers Cast Off 3/4 as the Others do your part of an Hourglass Circulate (almost always to move up to form Parallel Lines).

As for other parts...it's a grey area. I'd venture to say that there's 3-parts. Others may disagree. The inside part (2 of 3) is Outsides Trade as Centers Hinge and 1/2 Circulate. Which, of course is 2 parts for the Centers.

So, if someone were to fractionalize Tally-Ho, I'd expect 3 parts:

1. 1/2 Circulate;
2. Outsides Trade as Centers Hinge and 1/2 Box Circulate;
3. Center Line Cast Off 3/4 as Others do your part Hourglass Circulate.

It's okay in my opinion to have one part of the call to have multiple parts (i.e., 1/2 Circulate and Hinge considered as one part of the call).

For instance, take Percolate:

1. Circulate;
2. 1/2 Circulate;
3. Outsides Any Hand Turn Thru as Centers Hinge and Cross.