property Series.ItemByPos (Position as Long) as Serie
Returns a specific Serie from the Series collection, given its position.

TypeDescription
Position as Long A long expression that specifies the position (zero-based) of the Serie to request
Serie A Serie object being requested
The ItemByPos property allows you to access a specific Serie within a chart's Series collection by specifying its position in the collection. Instead of searching by name or looping through all series, you can directly get the series at a known position. The Count property gets the number of series. The Item property returns a specific Serie of the Series collection, giving its identifier. The Add method adds a Serie object to the collection and returns a reference to the newly created object. The Remove method removes a specific member from the Series collection, giving its identifier. The Clear method clears all series of the control. The Reset method clears the series, category axes and value axes without affecting the control's data. 

You can enumerate all series:

with Count providing the total number of series.